Separation Anxiety: An In-Class Game Designed To Help Students Discover ChromatographyMichael J. SamideAn in-class activity, designed on the basis of plate theory, allows students to physically separate coins on the basis of a provided partition coefficient. Students move coins between stationary and mobile phases to establish equilibrium conditions. The goal is to have students understand equilibration as it relates to separation, which can lead into a discussion of more complex topics.Samide, Michael J. J. Chem. Educ.2008, 85, 1512.

Chromatography |

Equilibrium

A Dramatic Classroom Demonstration of Limiting Reagent Using the Vinegar and Sodium Hydrogen Carbonate ReactionRomklao Artdej and Tienthong ThongpanchangThis demonstration, appropriate for high school chemistry level and recommended for a large classroom presentation, is designed to illustrate the concept of limiting reagent via a series of experiments in which increasing amounts of sodium bicarbonate are added to a fixed amount of vinegar is fixed until the volume of carbon dioxide generated remains constant. Artdej, Romklao; Thongpanchang, Tienthong. J. Chem. Educ.2008, 85, 1382.

Manual Data Processing in Analytical Chemistry: Linear CalibrationDora MelucciMost science students are familiar with Excel spreadsheets, but determining which of Excels statistical functions perform a calculation equivalent to a classical equation and calculating errors with Excel are not trivial exercises.Melucci, Dora. J. Chem. Educ.2008, 85, 1346.

Calibration |

Chemometrics |

Quantitative Analysis

Helping Students Assess the Relative Importance of Different Intermolecular InteractionsPaul G. JasienA semi-quantitative model has been developed to estimate the relative effects of dispersion, dipoledipole interactions, and H-bonding on the normal boiling points for a series of simple, straight-chain organic compounds. Application of this model may be useful in addressing student misconceptions related to the additivity of intermolecular interactions.Jasien, Paul G. J. Chem. Educ.2008, 85, 1222.

Chemometrics |

Molecular Properties / Structure |

Noncovalent Interactions |

Physical Properties

The Correlation of Binary Acid Strengths with Molecular Properties in First-Year ChemistryTravis D. FridgenThis article replaces contradictory explanations for the strengths of different binary acids in first-year chemistry textbooks with a single explanation that uses a BornHaber cycle involving homolyic bond dissociation energies, electron affinities, and ion solvation enthalpies to rationalize trends in the strengths of all binary acids.Fridgen, Travis D. J. Chem. Educ.2008, 85, 1220.

An Updated Equilibrium MachineEmeric SchultzDescribes a device that can demonstrate equilibrium and the Le Châtelier principle, as well as kinetic and thermodynamic concepts. The device consists of a leaf blower attached to a plastic container divided into two chambers by a barrier of variable size and form. Styrofoam balls can be exchanged across the barrier when various air pressures are applied by the blower.Schultz, Emeric. J. Chem. Educ.2008, 85, 1131.

Equilibrium |

Kinetics |

Thermodynamics

An Inexpensive Solution CalorimeterEmma Kavanagh, Sam Mindel, Giles Robertson, and D. E. Peter HughesDescribes the construction of a simple solution calorimeter, using a miniature bead thermistor as a temperature-sensing element, that has a response time of a few seconds and made it possible to carry out a thermometric reaction in under a minute.Kavanagh, Emma; Mindel, Sam; Robertson, Giles; Hughes, D. E. Peter. J. Chem. Educ.2008, 85, 1129.

EQVAPSIM: A Vapor–Liquid Equilibria of Binary Systems Computer Simulation by LabVIEWA. Belletti, R. Borromei, and G. InglettoReports the results of a program using LabVIEW software to simulate the construction of a phase diagram representing a liquidvapor equilibrium. The program models work in a real laboratory, including mistakes commonly made in this context.Belletti, A.; Borromei, R.; Ingletto, G. J. Chem. Educ.2008, 85, 879.

Equilibrium |

Thermodynamics |

Student-Centered Learning

A Simple Penny AnalysisNicholas C. Thomas and Stephen FaulkDescribes a simple procedure for determining the zinc composition of U.S. pennies in which the penny zinc core is dissolved in acid and the evolved hydrogen gas is collected by water displacement.Thomas, Nicholas C.; Faulk, Stephen. J. Chem. Educ.2008, 85, 817.

Yet Another Variation on the Electrolysis of Water at Iron NailsMark T. Stauffer and Justin P. FoxDescribes a variation on the electrolysis of water with iron nails in which a sharp contrast in the colors produced effectively demonstrates electrolysis and the diffusion of oxidized and reduced species from the electrodes.Stauffer, Mark T.; Fox, Justin P. J. Chem. Educ.2008, 85, 523.

NetorialsRebecca Ottosen, John Todd, Rachel Bain, Mike Miller, Liana Lamont, Mithra Biekmohamadi, and David B. ShawNetorials is a collection of about 30 online tutorials on general chemistry topics designed as a supplement for high school or college introductory courses. Each Netorial contains several pages of interactive instruction that includes animated mouse-overs, questions for students to answer, and manipulable molecular structures.Ottosen, Rebecca; Todd, John; Bain, Rachel; Miller, Mike; Lamont. Liana; Biekmohamadi, Mithra; Shaw, David B. J. Chem. Educ.2008, 85, 463.

Chemical Speciation and Calculation of pH of a Sport DrinkJosé L. Guiñón SeguraA recently published laboratory procedure allows students to see that the pointer function has a minimum value at the solution pH. However, the resolution of the pointer function requires the plotting the logarithmic concentration diagram, which is time-consuming and tedious.Segura, José L Guiñón. J. Chem. Educ.2008, 85, 371.

Determining the Solubility Product of Fe(OH)3: An Equilibrium Study with Environmental SignificanceMichelle Meighan, Joseph MacNeil, and Renee FalconerThis study explores the environmental impact of acidic mine drainage by investigating the relationship between pH and the aqueous solubility of heavy metals. Students precipitate Fe(OH)3 from acidic FeCl3 and NaOH and use the concentrations of ferric and hydroxide ionsdetermined through pH and flame spectroscopyto calculate the Ksp of Fe(OH)3.Meighan, Michelle; MacNeil, Joseph; Falconer, Renee. J. Chem. Educ.2008, 85, 254.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Precipitation / Solubility |

Spectroscopy

Connecting Solubility, Equilibrium, and Periodicity in a Green, Inquiry Experiment for the General Chemistry LaboratoryKristen L. Cacciatore, Jose Amado, Jason J. Evans, and Hannah SevianPresents a novel first-year chemistry experiment that asks students to replicate procedures described in sample lab reports that lack essential information. This structure is designed to promote students' experimental design and data analysis skills as well as their understanding of the importance and essential qualities of written and verbal communication between scientists.Cacciatore, Kristen L.; Amado, Jose; Evans, Jason J.; Sevian, Hannah. J. Chem. Educ.2008, 85, 251.

Equilibrium |

Green Chemistry |

Periodicity / Periodic Table |

Solutions / Solvents |

Stoichiometry |

Titration / Volumetric Analysis

Scientific–Chemical Viewpoints Regarding Smoking: A Science Laboratory for AllRon BlonderThis article describes a lab that examines the acidity of cigarette smoke as well as solid particles and vapor phase substances found therein, and simulates the effects of smoking on the lungs. The aim of this activity is to expose adolescents to the scientific aspects of smoking and the relevance of chemistry in everyday life.Blonder, Ron. J. Chem. Educ.2008, 85, 248.

Acids / Bases |

Consumer Chemistry |

Gases |

Laboratory Equipment / Apparatus |

pH |

Applications of Chemistry |

Student-Centered Learning

The Role of Water Chemistry in Marine Aquarium Design: A Model System for a General Chemistry ClassJeffrey J. Keaffaber, Ramiro Palma, and Kathryn R. WilliamsWater chemistry is central to aquarium design, and it provides many potential applications for discussion in undergraduate chemistry and engineering courses. This article uses a hypothetical tank to house ocean sunfish as a model to show students the calculations and other considerations that are needed when designing a marine aquarium.Keaffaber, Jeffrey J.; Palma, Ramiro; Williams, Kathryn R. J. Chem. Educ.2008, 85, 225.

Acids / Bases |

Aqueous Solution Chemistry |

Consumer Chemistry |

Oxidation / Reduction |

Stoichiometry |

Water / Water Chemistry

A Simplified Model To Predict the Effect of Increasing Atmospheric CO2 on Carbonate Chemistry in the OceanBrian J. Bozlee, Maria Janebo, and Ginger JahnThe chemistry of dissolved inorganic carbon in seawater is reviewed and used to predict the potential effect of rising levels of carbon dioxide in the atmosphere. It is found that calcium carbonate may become unsaturated in cold surface seawater by the year 2100, resulting in the destruction of calcifying organisms such as coral.Bozlee, Brian J.; Janebo, Maria; Jahn, Ginger. J. Chem. Educ.2008, 85, 213.

Applications of Chemistry |

Aqueous Solution Chemistry |

Atmospheric Chemistry |

Equilibrium |

Green Chemistry |

Water / Water Chemistry

Reaction Order Ambiguity in Integrated Rate PlotsJoe LeeThis article provides a theoretical and statistical justification for the necessity of monitoring a reaction to a substantial fraction of completion if integrated rate plots plots are to yield unambiguous orders.Lee, Joe. J. Chem. Educ.2008, 85, 141.

Chemometrics |

Kinetics |

Rate Law

Using the Science Writing Heuristic To Improve Students' Understanding of General EquilibriumJames A. Rudd, II, Thomas J. Greenbowe, and Brian M. HandThis study examines the performance of students using the Science Writing Heuristic approach, which facilitates scientific inquiry by structuring the laboratory notebook in a format that guides students to answer directed questions, on lecture exams and a laboratory practical exam on chemical equilibrium.Rudd, James A., II; Greenbowe, Thomas J.; Hand, Brian M. J. Chem. Educ.2007, 84, 2007.

The Chemistry of Paper PreservationHenry A. CarterThis article examines the applications of chemistry to paper preservation. The acid-catalyzed hydrolysis of cellulose accounts for the deterioration of paper in library books and other written records. To combat this threat to our written heritage, new permanent papers have been developed that are relatively chemically stable and undergo a very slow rate of deterioration. Carter, Henry A. J. Chem. Educ.2007, 84, 1937.

Acids / Bases |

Applications of Chemistry |

Aqueous Solution Chemistry |

Free Radicals |

Gas Chromatography |

HPLC |

pH |

Kinetics |

Rate Law

Carbon Dioxide FountainSeong-Joo Kang and Eun-Hee RyuThis article presents the development of a carbon dioxide fountain that, unlike the traditional ammonia fountain, is odorless and uses consumer chemicals. This experiment also allows students to see evidence of a gaseous reagent being consumed when a pressure sensor is available.Kang, Seong-Joo; Ryu, Eun-Hee. J. Chem. Educ.2007, 84, 1671.

Acids / Bases |

Consumer Chemistry |

Gases |

Laboratory Equipment / Apparatus |

Reactions

The Use of Conjugate Charts in Transfer Reactions: A Unified ApproachMichael I. AllnuttRedox reactions are discussed in terms of the relative strengths of the oxidant, the reductant, and their conjugates; a conjugate chart is a convenient and useful way of doing this. A similar chart for acids and bases that can be applied in the same manner is proposed.Allnutt, Michael I. J. Chem. Educ.2007, 84, 1659.

Acids / Bases |

Electrolytic / Galvanic Cells / Potentials |

Oxidation / Reduction |

Brønsted-Lowry Acids / Bases

The Use of Limits in an Advanced Placement Chemistry CoursePaul S. Matsumoto, Jonathan Ring, and Jia Li (Lily) ZhuThis article describes the use of limits in topics usually covered in advanced placement or first-year college chemistry. This approach supplements the interpretation of the graph of an equation since it is usually easier to evaluate the limit of a function than to generate its graph.Matsumoto, Paul S.; Ring, Jonathan; Zhu, Jia Li (Lily). J. Chem. Educ.2007, 84, 1655.

Exception to the Le Châtelier PrincipleDavid S. Corti and Mark J. UlineDisagreement regarding an apparent exception to the Le Chtelier principle involving the effects of nonideality on the direction in which the ammonia synthesis reaction shifts upon addition of infinitesimal and finite quantities of nitrogen at constant pressure and temperature. Corti, David S.; Uline, Mark J. J. Chem. Educ.2007, 84, 1427.

Equilibrium

Exception to the Le Châtelier PrincipleThomas R. HerrintonDisagreement regarding an apparent exception to the Le Chtelier principle involving the effects of nonideality on the direction in which the ammonia synthesis reaction shifts upon addition of infinitesimal and finite quantities of nitrogen at constant pressure and temperature. Herrinton, Thomas R. J. Chem. Educ.2007, 84, 1427.

Equilibrium |

Gases

Exception to the Le Châtelier PrincipleThomas R. HerrintonDisagreement regarding an apparent exception to the Le Chatelier principle involving the effects of nonideality on the direction in which the ammonia synthesis reaction shifts upon addition of infinitesimal and finite quantities of nitrogen at constant pressure and temperature. Herrinton, Thomas R. J. Chem. Educ.2007, 84, 1427.

Imidazole as a pH Probe: An NMR Experiment for the General Chemistry LaboratoryWilliam J. Hagan, Jr., Dennis L. Edie, and Linda B. CooleyAn experiment is described that employs the 1H-NMR signal of aqueous imidazole to determine the pH of an unknown solution. The procedure involves the preparation of a calibration curve, which is then used for the analysis of the unknown(s).Hagan, William J., Jr.; Edie, Dennis L.; Cooley, Linda B. J. Chem. Educ.2007, 84, 1188.

Defining and Teaching pHRichard F. BurtonAt an elementary level, pH and the algebra of equilibria can be simply and correctly taught, without logarithms, in terms of the modern, operationally-defined pH scale that underlies laboratory measurement and relates to activities.Burton, Richard F. J. Chem. Educ.2007, 84, 1129.

Acids / Bases |

pH |

Aqueous Solution Chemistry

The Chemistry of Swimming Pool MaintenanceCarl Salter and David L. LanghusThis paper examines the key ideas behind swimming pool chemistry -- the central importance of pH and its effect on chlorine sanitation and calcium carbonate solubility. The paper also reviews the analytical procedures and common practices used to monitor and control pool chemistry or correct problems.Salter, Carl; Langhus, David L. J. Chem. Educ.2007, 84, 1124.

Acids / Bases |

Applications of Chemistry |

Aqueous Solution Chemistry |

Dyes / Pigments |

pH |

Photochemistry |

Precipitation / Solubility |

Water / Water Chemistry

Peer-Developed and Peer-Led Labs in General ChemistryLorena Tribe and Kim KostkaDescribes a student-developed and led laboratory curriculum as a model for producing a more student-centered and rich laboratory experience in general chemistry laboratories.Tribe, Lorena; Kostka, Kim. J. Chem. Educ.2007, 84, 1031.

Thermochemical Analysis of Neutralization Reactions: An Introductory Discovery ExperimentKenneth V. Mills and Louise W. GuilmetteDescribes a guided-inquiry laboratory pedagogy in which students discover chemical concepts in the lab and the instructor uses their pooled data to guide the lecture portion of the course. This method is illustrated by an experiment that reinforces students' understanding of stoichiometry and allows them to discover neutralization reactions and thermochemistry.Mills, Kenneth V.; Guilmette, Louise W. J. Chem. Educ.2007, 84, 326.

Acids / Bases |

Stoichiometry |

Calorimetry / Thermochemistry |

Acids / Bases

More Thoughts on the Narra Tree FluorescenceA. Ulises AcuñaThe source of L. nephriticum and the substance responsible for the intense blue fluorescence in an earlier published demonstration may require further consideration.Acuña, A. Ulises. J. Chem. Educ.2007, 84, 231.

Fluorescence Spectroscopy |

Natural Products |

Plant Chemistry |

Solutions / Solvents |

UV-Vis Spectroscopy |

Acids / Bases

Titration of a Solid Acid Monitored By X-Ray DiffractionKeenan E. Dungey and Paul EpsteinPresents a solid-state laboratory in which students react fixed amounts of zirconium phosphate with increasing equivalents of NaOH(aq). From X-ray diffraction patterns, students calculate the interplanar spacings before and after the reaction. The spacings increase until the molar equivalence point is reached, indicating incorporation of the sodium ion into the crystal.Dungey, Keenan E.; Epstein, Paul. J. Chem. Educ.2007, 84, 122.

Let Us Give Lewis Acid–Base Theory the Priority It DeservesAlan A. ShafferThe Lewis concept is simple yet powerful in its scope, and can be used to help beginning students understand reaction mechanisms more fully. However, traditional approaches to acid-base reactions at the introductory level ignores Lewis acid-base theory completely, focusing instead on proton transfer described by the Br?nsted-Lowry concept.Shaffer, Alan A. J. Chem. Educ.2006, 83, 1746.

Astrochemistry Examples in the ClassroomReggie L. HudsonIn this article some recent developments in astrochemistry are suggested as examples for the teaching of acid-base chemistry, molecular structure, and chemical reactivity. Suggestions for additional reading are provided, with an emphasis on readily-accessible materials.Hudson, Reggie L. J. Chem. Educ.2006, 83, 1611.

Teaching Physical Chemistry Experiments with a Computer Simulation by LabVIEWA. Belletti, R. Borromei, and G. InglettoThis article reports on a computer simulation developed with the software LabVIEW of the physical chemistry experiment regarding the vapor pressure measurements of a pure liquid as a function of temperature, as well as a system of data collecting that emphasizes the similarities between the virtual and real experiment.Belletti, A.; Borromei, R.; Ingletto, G. J. Chem. Educ.2006, 83, 1353.

Equilibrium |

Laboratory Computing / Interfacing |

Liquids |

Thermodynamics |

Gases |

Student-Centered Learning

Equilibrium Constants and Water Activity RevisitedDavid KeeportsSubtle arguments based upon the use of chemical potentials show that numerical values of solute molar concentrations can be used as good approximate activities in equilibrium calculations for reactions involving dilute solutions.Keeports, David. J. Chem. Educ.2006, 83, 1290.

Weak Acid pKa Determination Using Capillary Zone ElectrophoresisMike SolowIn this experiment, students use capillary zone electrophoresis to determine the effective mobility of benzoic acid at two different hydrogen ion concentrations. A plot of these data yields the pKa of benzoic acid.Solow, Mike. J. Chem. Educ.2006, 83, 1194.

Acids / Bases |

Aqueous Solution Chemistry |

Carboxylic Acids |

Electrophoresis |

Instrumental Methods

Lecture Templates: Convenient Partial Lecture Delivery SystemElzbieta Cook and Robert L. CookReports on the use of two forms of PowerPoint lecture presentationsa complete version used by the lecturer and a corresponding partial version available in advance to students. Pre-prepared lecture presentations allow for the sharing of lecture materials among teaching faculty and ensure consistency among several lecture sections in team taught courses.Cook, Elzbieta; Cook, Robert L. J. Chem. Educ.2006, 83, 1176.

Equilibrium |

Lewis Structures |

Professional Development

Two "Gas-in-a-Bag" Reactions To Show the Predictive Power of the Relative AcidBase Strength ChartBrett CriswellDescribes a demonstration in which two different pairs of solid chemicals mixed in two different Ziploc bags in the presence of a small quantities of water react to produce gases. Students are informed that the reactions are BrnstedLowry acidbase type reactions and must determine which member in each pair will act as the acid and which as the base.Criswell, Brett. J. Chem. Educ.2006, 83, 1167.

Factors That Influence Relative Acid Strength in Water: A Simple ModelMichael J. MoranThe pKa's of diverse aqueous acids HA correlate well with the sum of two gas-phase properties: the HA bond-dissociation enthalpy and the electron affinity of the A radical. It is suggested that rather than bond strength alone or bond polarity, the sum of the enthalpies of these two steps is a fairly good indicator of relative acidity.Moran, Michael J. J. Chem. Educ.2006, 83, 800.

Acids / Bases |

Aqueous Solution Chemistry |

Atomic Properties / Structure |

Free Radicals

(Strept)Avidin–Biotin: Two Interrelated Experiments for the Introductory Chemistry LaboratoryDavid E. Hansen, Dengda Tang, Jon A. Sanborn, and Mark D. MarshallDescribes a two-experiment sequence focusing on the noncovalent complex between the egg white protein avidin (or the similar protein streptavidin, which is expressed by the bacterium Streptomyces avidinii) and the essential cofactor biotin. The equilibrium constant for the binding of HABA to avidin is calculated from the data collected.Hansen, David E.; Tang, Dengda; Sanborn, Jon A.; Marshall, Mark D. J. Chem. Educ.2006, 83, 777.

pH Paradoxes: Demonstrating That It Is Not True That pH ≡ -log[H+]Christopher G. McCarty and Ed VitzSix demonstrations highlighting paradoxes that arise if pH is incorrectly defined as -log[H+] are presented as justification for the recommendation that pH should be correctly defined as pH = -log aH+ in textbooks.McCarty, Christopher G.; Vitz, Ed. J. Chem. Educ.2006, 83, 752.

A New Java Animation in Peer-Reviewed JCE WebWareWilliam F. Coleman and Edward W. FedoskyJust added to JCE WebWare, Computer Simulations of Salt Solubility uses a Java applet and Web browser to present an animated illustration of differences in the solubility of salts due to differences in the entropy of solvation.Coleman, William F.; Fedosky, Edward W. J. Chem. Educ.2006, 83, 173.

Presumptive and Confirmatory Drug TestsCraig AndersonTests for illegal drugs were performed on unknowns obtained from over-the-counter cold medicines. Substances that tested positive for the qualitative Marquis color test were found to be false positives for illegal substances, while scopolamine hydrochloride shows a false positive for cocaine hydrochloride with the cobalt thiocyanate reagent. Anderson, Craig. J. Chem. Educ.2005, 82, 1809.

Synthesis and Physical Properties of Liquid Crystals: An Interdisciplinary ExperimentGerald R. Van Hecke, Kerry K. Karukstis, Hanhan Li, Hansford C. Hendargo, Andrew J. Cosand, and Marja M. FoxThis experiment features an investigative approach designed for the introductory science or engineering major and integrates concepts in the fields of chemistry, biology, and physics. Derived from faculty research interests, this novel experiment gives students the opportunity to draw conclusions from tests performed to illustrate the connection between molecular structure and macroscopic properties. The chemical synthesis of the compounds studied further enhances the connection between molecular structure and macroscopic physical properties. The results of two separate physical measurements, refractometry and absorption spectroscopy, are combined to calculate a microscopic, but very practical, property of chiral nematic liquidsthe pitch of the helix formed in the liquid crystalline phase.Van Hecke, Gerald R.; Karukstis, Kerry K.; Li, Hanhan; Hendargo, Hansford C.; Cosand, Andrew J.; Fox, Marja M. J. Chem. Educ.2005, 82, 1349.

Chirality / Optical Activity |

Crystals / Crystallography |

Molecular Properties / Structure |

UV-Vis Spectroscopy |

Acids / Bases |

Esters |

Physical Properties |

Physical Properties

Equilibria That Shift Left upon Addition of More ReactantJeffrey E. LacyMost textbook presentations of Le Chtelier's principle in general and physical chemistry do not include a discussion of constant pressure conditions for which addition of a reactant can shift the equilibrium to the left. We propose presentations of isothermal, open systems at constant pressure for both levels of study by using concepts and skills that the respective students already possess. In addition, we derive novel criteria based on the stoichiometry of the reaction that can be used to identify those equilibria that will shift left upon addition of more reactant. Lacy, Jeffrey E. J. Chem. Educ.2005, 82, 1192.

Cross-Proportions: A Conceptual Method for Developing Quantitative Problem-Solving SkillsElzbieta Cook and Robert L. CookThis paper focuses attention on the cross-proportion (C-P) method of mathematical problem solving, which was once widely used in chemical calculations. We propose that this method regain currency as an alternative to the dimensional analysis (DA) method, particularly in lower-level chemistry courses. In recent years, the DA method has emerged as the only problem solving mechanism offered to high-school and general chemistry students in contemporary textbooks, replacing more conceptual methods, C-P included. Cook, Elzbieta; Cook, Robert L. J. Chem. Educ.2005, 82, 1187.

Learning Theories |

Stoichiometry |

Chemometrics |

Student-Centered Learning

The Reaction Quotient Is Unnecessary To Solve Equilibrium ProblemsPaul S. MatsumotoWhile my paper states that the reaction quotient (Q) is not needed to solve equilibrium problems, it does not imply that Q is not valuable. In fact, when I teach this topic to my AP chemistry class, I initially use Q to solve the problem, then mention the alternative method described in the paper.Matsumoto, Paul S. J. Chem. Educ.2005, 82, 1150.

Equilibrium |

Learning Theories |

Mathematics / Symbolic Mathematics

The Reaction Quotient Is Unnecessary To Solve Equilibrium Problems: No Problems with QRobert LedererMr. Matsumotos students are to be congratulated for discerning an interesting mathematical procedure. Exclusively utilizing this algorithm, however, short-cuts the understanding of the chemistry involved. Students of chemistry should be challenged to understand why something occurs, and not to be satisfied with how to perform the often mundane calculations.Lederer, Robert. J. Chem. Educ.2005, 82, 1149.

Equilibrium Constants and Water ActivityDavid KeeportsGeneral chemistry instructors are faced with a dilemma when introducing the topic of equilibrium constants: These constants are correctly written in terms of activities, yet activity is a complex topic better treated rigorously in a physical chemistry course than superficially in a general chemistry course. Thus, to introduce equilibrium calculations, it is necessary to use approximate forms for equilibrium constants. However, I find that some commonly used textbooks provide incorrect arguments leading to approximate equilibrium constants for aqueous reactions.Keeports, David. J. Chem. Educ.2005, 82, 999.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium |

Water / Water Chemistry

JavaScript Programs To Calculate Thermodynamic Properties Using Cubic Equations of StateCubic equations of state are widely used by chemists and chemical engineers to predict the thermodynamic properties of both pure substances and mixtures. In particular, these equations enable predictions concerning the temperature and pressure at which vaporliquid equilibrium occurs. These two educational JavaScript programs perform calculations using cubic equations of state and, equally importantly, explain how the calculations are performed.J. Chem. Educ.2005, 82, 960.

Enrichment / Review Materials |

Equilibrium |

Thermodynamics

JavaScript Programs To Calculate Thermodynamic Properties Using Cubic Equations of StatePatrick J. BarrieIn this article, two JavaScript programs are described. The first program gives students the choice of five different cubic equations of state and performs calculations for pure substances. The second program predicts vaporliquid equilibrium for binary mixtures using a choice of three modern equations of state and the van der Waals mixing rules.Barrie, Patrick J. J. Chem. Educ.2005, 82, 958.

Enrichment / Review Materials |

Thermodynamics |

Equilibrium

Teaching pH Measurements with a Student-Assembled Combination Quinhydrone ElectrodeFritz Scholz, Tim Steinhardt, Heike Kahlert, Jens R. Pörksen, and Jürgen BehnertA combination pH electrode that can be assembled by the student is described. It consists of a glass holder and two sensors in the form of rubber stoppers that contain quinhydrone and graphite. The combination electrode is suitable to teach potentiometric measurements, pH measurements, and the interplay of acidbase and redox equilibria. The electrode meets highest safety standards and overcomes the troubles associated with the use of the conventional quinhydrone electrode.Scholz, Fritz; Steinhardt, Tim; Kahlert, Heike; Pörksen, Jens R.; Behnert, Jürgen. J. Chem. Educ.2005, 82, 782.

Procedure for Decomposing a Redox Reaction into Half-ReactionsIlie Fishtik and Ladislav H. BerkaThe principle of stoichiometric uniqueness provides a simple algorithm to check whether a simple redox reaction may be uniquely decomposed into half-reactions in a single way. For complex redox reactions the approach permits a complete enumeration of a finite and unique number of ways a redox reaction may be decomposed into half-reactions. Several examples are given. Fishtik, Ilie; Berka, Ladislav H. J. Chem. Educ.2005, 82, 553.

Stoichiometry |

Equilibrium |

Electrochemistry |

Oxidation / Reduction |

Reactions |

Thermodynamics

The Reaction Quotient Is Unnecessary To Solve Equilibrium ProblemsPaul S. MatsumotoThe traditional method to determine the equilibrium concentration of chemicals in a reaction, given the equilibrium constant and the initial concentration of chemicals in the reaction, involves the determination of the reaction quotient. This article will demonstrate that this step may be eliminated; thereby simplifying the algorithm to solve such problems. Such a reduction in the complexity of the algorithm may result in more students successfully being able to solve such problems. Matsumoto, Paul S. J. Chem. Educ.2005, 82, 406.

Equilibrium |

Learning Theories |

Chemometrics

Putting A Human Face on EquilibriumNeil GlicksteinA short biography of chemist Fritz Haber is used to personalize the abstract concepts of equilibrium chemistry for high school students in an introductory course. In addition to giving the HaberBosch process an historic, an economic, and a scientific background the reading and subsequent discussion allows students for whom the human perspective is of paramount importance a chance to investigate the irony of balance or equilibrium in Haber's life story.Glickstein, Neil. J. Chem. Educ.2005, 82, 391.

Equilibrium

Analysis of Natural Buffer Systems and the Impact of Acid Rain. An Environmental Project for First-Year Chemistry StudentsDavid C. Powers, Andrew T. Higgs, Matt L. Obley, Phyllis A. Leber, Kenneth R. Hess, and Claude H. YoderThe purpose of this project is to investigate the basic principles involved in acidbase buffer systems within the context of an environmental issue. It is designed for use in an introductory chemistry course. The students will learn about acidbase interactions and examine how a buffer system composed of a weak acid and its conjugate base can neutralize large quantities of strong acid while resisting drastic change in the pH of the system. Students will also analyze experimentally the various components of the most commonly occurring natural buffer system.Powers, David C.; Higgs, Andrew T.; Obley, Matt L.; Leber, Phyllis A.; Hess, Kenneth R.; Yoder, Claude H. J. Chem. Educ.2005, 82, 274.

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Capillary Electrophoresis Analysis of Cations in Water Samples. An Experiment for the Introductory LaboratoryChristopher J. Pursell, Bert Chandler, and Michelle M. BusheyThis experiment can be done in a lab, as a "dry-lab", or as an in-class exercise. Students explore a number of basic separation topics and work with figures of merit for real and meaningful samples. We have adopted a strategy where students encounter various instruments and methods of analyses multiple times throughout the curriculum. The level of sophistication in the exposures increases with the experience level of the students. Through this repeated exposure students will gain a better and fuller understanding of these methods than they would with a single exposure to the technique in the analytical or instrumental laboratory. Pursell, Christopher J.; Chandler, Bert; Bushey, Michelle M. J. Chem. Educ.2004, 81, 1783.

Electrophoresis |

Quantitative Analysis |

Separation Science |

Chemometrics |

Water / Water Chemistry

Statistical Comparison of Data in the Analytical LaboratoryMichael J. SamideIn this article, an experiment designed to provide students with an experience involving statistical treatment of data is described. This experiment allows students to compare 11 different techniques for measuring specific volumes of water. Replicate measurements are taken for each technique and comparisons are made both within a data set and between different data sets. Through calculation of t-values, students are able to draw conclusions about the precision and accuracy of these various techniques.Samide, Michael J. J. Chem. Educ.2004, 81, 1641.

Chemometrics

Playing Card EquilibriumFrank L. LambertFrom experience, I am hypersensitive to the misconceptions of students and instructors that can be caused when playing cards are used in teaching chemistry. The root of such errors lies in overlooking the non-mobile, non-energetically-interacting nature of pieces of cardboard. Only if they are being shuffled can cards serve as some sort of analogy to molecular behavior in chemistry.Lambert, Frank L. J. Chem. Educ.2004, 81, 1569.

Use of a Tea Infuser To Submerge Low-Density Dry IceCarl P. FictorieA tea infuser is used as a container to hold low-density dry ice. When used with the classic demonstration where dry ice is used to acidify a solution in a graduated cylinder, the dry ice is suspended in the middle of the cylinder, allowing the solution in the upper half of the cylinder to change color while the lower half remains unchanged. Phase changes, acidbase chemistry, and diffusion phenomena are all illustrated. Fictorie, Carl P. J. Chem. Educ.2004, 81, 1473.

Acids / Bases |

Aqueous Solution Chemistry |

Laboratory Equipment / Apparatus |

Phases / Phase Transitions / Diagrams

Using Clinical Cases To Teach General ChemistryBrahmadeo Dewprashad, Charles Kosky, Geraldine S. Vaz, and Charlotte L. MartinThis article describes how a fact-based clinical case was effectively used to motivate and enrich the classroom experience and review many of the concepts covered in general chemistry. The case involves an elderly patient who was brought to the emergency room. The results of his physical examination and laboratory analysis of his blood are presented. The students, in peer-led groups, work through the chemical principles involved in the doctor's diagnosis and treatment options for the patient. The article describes the case study, instructors' observations, and students' perception of the activity. Dewprashad, Brahmadeo; Kosky, Charles; Vaz, Geraldine S.; Martin, Charlotte L. J. Chem. Educ.2004, 81, 1471.

Acids / Bases |

Drugs / Pharmaceuticals |

Equilibrium |

Kinetics |

Medicinal Chemistry

Unified Approximations: A New Approach for Monoprotic Weak Acid–Base EquilibriaHarry L. Pardue, Ihab N. Odeh, and Teweldemedhin M. TesfaiThis article describes a new approach to approximate calculations for monoprotic acidbase equilibria in otherwise pure water. The new approach, identified herein as unified approximations, uses a simple decision criterion to select between situations that should be treated as deprotonation and protonation reactions. The remaining treatment takes account of changes in concentrations of conjugate acidbase pairs for all situations and ignores autoprotolysis only for situations for which the analytical concentration of either the conjugate acid or conjugate base will always be larger than zero. Pardue, Harry L.; Odeh, Ihab N.; Tesfai, Teweldemedhin M. J. Chem. Educ.2004, 81, 1367.

Acids / Bases |

Equilibrium |

Chemometrics

Reaction to Why Do We Teach Equilibrium Calculations?Stephen J. Hawkes"Rigor" in introductory chemistry is often equated with quantitation. Consequently the understanding of chemical reactions and properties is obscured. This was illustrated by Stumpo who asked students to calculate ?E of a reaction, and then on another question on the same test asked a question aimed at its meaning. 77% of the students calculated correctly, but only 24% showed understanding of its meaning. The ability to calculate a number does not measure understanding of the number. Hawkes, Stephen J. J. Chem. Educ.2004, 81, 1265.

Equilibrium |

Chemometrics

Reaction to Why Do We Teach Equilibrium Calculations? Don L. LewisA recently published correspondence by Stephen J. Hawkes on teaching equilibrium calculations troubles me. Hawkes dismisses equilibrium calculations as mere algorithms, best deferred until the student can use computer programs. I find it difficult to believe that a computer program enhances understanding. From a chemists point of view, the equilibrium condition is a limit, a limit that (because of stochastic considerations) does not exist. It might be better to make the reaction quotient statement using < or > but the use of those relations is delayed until quantum mechanics.Lewis, Don L. J. Chem. Educ.2004, 81, 1265.

Using a Graphing Calculator To Determine a First-Order Rate Constant: Author ReplyJosé E. Cortés-FigueroaWhen technology is used to help with mathematical calculations, the emphasis must be on the concepts being learned rather than simply the procedures. In our approach we are attempting to help students learn more about the concept and also to attain data analysis skills they will need in the future. Cortés-Figueroa, José E. J. Chem. Educ.2004, 81, 485.

Simple Experiments To Demonstrate Proton Flux in Pseudomonas after Alkaline or Acidic StressGabriela Previtali, Walter Giordano, and Carlos E. DomenechA laboratory experiment to ascertain the bacterial response to the stress produced by suspension in different pH solutions has been developed. This laboratory experiment has the pedagogical advantage of giving chemistry students experience with the application of various pH levels to a biological system and enables the students to expand their understanding of pH to mean more than a strictly chemical concept. Previtali, Gabriela; Giordano, Walter; Domenech, Carlos E. J. Chem. Educ.2003, 80, 1468.

Acids / Bases

Carbon Dioxide Flooding: A Classroom Case Study Derived from Surgical PracticeRobert C. KerberThe surgical opening in open-heart surgery is often flooded with carbon dioxide gas to avoid air embolisms when the heart is closed and restarted. This practice can be used in chemistry courses to illustrate concepts of gas density, solubility, and acidbase equilibria, including buffering.Kerber, Robert C. . J. Chem. Educ.2003, 80, 1437.

Acids / Bases |

Aqueous Solution Chemistry |

Gases |

Medicinal Chemistry |

Nonmajor Courses |

Applications of Chemistry

Canadian Tire Money: An Analogy for Use When Discussing Weak Acid–Strong Base TitrationsArthur M. LastIn this article, use is made of the practice of one well-known Canadian retail chain in returning to its customers a small percentage of an item's purchase price in the form of imitation bank notes that can subsequently be spent in the chain's stores. An analogy is drawn between this practice and the determination of the pKa of a weak acid by titrating it with a strong base, taking into account the hydrolysis of the anion produced. Last, Arthur M. J. Chem. Educ.2003, 80, 1403.

Acids / Bases |

Titration / Volumetric Analysis

Why Do We Teach Equilibrium Calculations?Stephen J. HawkesIs there any substantial value to students in learning these calculations? Is there value enough to warrant inclusion in the one year of introductory chemistry?Hawkes, Stephen J. J. Chem. Educ.2003, 80, 1381.

Palm-Based Data Acquisition Solutions for the Undergraduate Chemistry LaboratorySusan Hudgins, Yu Qin, Eric Bakker, and Curtis ShannonHandheld computers provide a compact and cost-effective means to log data in the undergraduate chemistry laboratory. Handheld computers have the ability to record multiple forms of data, be programmed for specific projects, and later have data transferred to a personal computer for manipulation and analysis.Hudgins, Susan; Qin, Yu; Bakker, Eric; Shannon, Curtis. J. Chem. Educ.2003, 80, 1303.

Acids / Bases |

Electrochemistry |

Instrumental Methods |

Laboratory Computing / Interfacing |

Laboratory Equipment / Apparatus

Playing-Card EquilibriumRobert M. HansonA simple hands-on simulation suitable for either classroom use or laboratory investigation involves using a standard deck of playing cards to explore the statistical aspects of equilibrium. Concepts that can be easily demonstrated include fluctuation around a most probable distribution, Le Chtelier's principle, the equilibrium constant, prediction of the equilibrium constant based on probability, and the effect of sample size on equilibrium fluctuations. Hanson, Robert M. J. Chem. Educ.2003, 80, 1271.

Equilibrium |

Statistical Mechanics |

Thermodynamics

SpecScan: A Utility Program for Generating Numerical Data from Printed Forms of Spectra or Other SignalsConstantinos E. EfstathiouSpecSpan is a utility program for Microsoft Windows that generates numerical data from printed spectra or other plots found as figures in text, chart recordings, or freehand drawings. SpecScan can process bitmap (.BMP) images of such figures and drawings. After a brief interaction with the user, it generates and exports numerical data as Excel (.XLS) or text (.TXT) files.Efstathiou, Constantinos E. J. Chem. Educ.2003, 80, 1093.

Two Linear Correlation CoefficientsRobert de LevieIn fitting data to a straight line, many calculators and computer programs display a linear correlation coefficient. Two types of linear correlation coefficients are discussed, one often useful in chemical calculations, the other usually not. de Levie, Robert. J. Chem. Educ.2003, 80, 1030.

Principal Species and pH in Acid–Base SolutionsRobert M. HansonWeb page that allows one to determine the concentrations of principal species in a variety of solutions or mixtures of solutions; also allows a virtual titration.Hanson, Robert M. J. Chem. Educ.2002, 79, 1486.

Acid-Base Indicators: A New Look at an Old TopicAra S. Kooser, Judith L. Jenkins, and Lawrence E. WelchAn acid-base titration in which students choose the best indicator from a set of possibilities using a conductivity probe to help them make an informed choice.Kooser, Ara S.; Jenkins, Judith L.; Welch, Lawrence E. J. Chem. Educ.2001, 78, 1504.

Acids / Bases |

Conductivity |

Dyes / Pigments |

Laboratory Computing / Interfacing |

Titration / Volumetric Analysis |

Quantitative Analysis

The Relative Acidities of Water and MethanolHenry I. AbrashAnalysis of the disparity between the way the acidity constant of water is presented in general chemistry and organic chemistry textbooks.Abrash, Henry I. J. Chem. Educ.2001, 78, 1496.

Is Every Transparent Liquid Water?Muhamad Hugerat and Sobhi BasheerComparisons of the properties (polarity, electric conductivity, color change due to the presence of an acid-base indicator, and electrolysis) of three transparent and colorless liquids: water, glycerol, hexane, and ethanol.Hugerat, Muhamad; Basheer, Sobhi. J. Chem. Educ.2001, 78, 1041.

Assessing Students' Conceptual Understanding of Solubility EquilibriumAndrés RavioloA problem about solubility equilibrium is presented as a resource for the evaluation of students; it involves macroscopic, microscopic, and symbolic levels of representation, and allows one to assess whether students have acquired an adequate conceptual understanding of the phenomenon.Raviolo, Andrés. J. Chem. Educ.2001, 78, 629.

What's Been Happening to Undergraduate MathematicsDavid M. BressoudAn overview of some of the changes that have been occurring in undergraduate mathematics education; based on a workshop held by the Mathematical Association of America to determine what chemists expect their students to learn from undergraduate mathematics courses in terms of understanding, content, and use of technology. Bressoud, David M. J. Chem. Educ.2001, 78, 578.

Learning Theories |

Mathematics / Symbolic Mathematics |

Chemometrics

Acids and Bases in Layers: The Stratal Structure of an Ancient TopicWobbe de Vos and Albert PilotThis article identifies and discusses six successive "layers" that can be recognized in chapters on acids and bases in general chemistry textbooks, each the result of what once was a modernization; the cumulative result of these layers has become problematic, and some learning problems that students have when studying acids and bases become comprehensible when viewed from this perspective. de Vos, Wobbe; Pilot, Albert. J. Chem. Educ.2001, 78, 494.

Understanding Solubility through Excel SpreadsheetsPamela BrownThis article describes assignments related to the solubility of inorganic salts that can be given in an introductory general chemistry course. These assignments address the need for math, graphing, and computer skills in the chemical technology program by developing skill in the use of Microsoft Excel to prepare spreadsheets and graphs and to perform linear and nonlinear curve-fitting. Brown, Pamela. J. Chem. Educ.2001, 78, 268.

Aqueous Solution Chemistry |

Chemometrics |

Precipitation / Solubility

The State of Division of Solids and Chemical EquilibriaJoão C. M. Paiva and Victor M. S. GilAn experiment and a computer simulation are presented to address a counterintuitive situation often encountered when teaching chemical equilibria. This is prompted by the question "How can the subdivision of a solid reactant affect the reaction rate and not the composition of the equilibrium state?" Paiva, João C. M.; Gil, Victor M. S. J. Chem. Educ.2001, 78, 222.

Equilibrium |

Kinetics |

Laboratory Computing / Interfacing

Modification of Small-Scale One-Pot Reactions to an Inquiry-Based Laboratory ExerciseC. Jayne WilcoxStudents are given an initial handout and asked to complete a short, attention-getting exercise. They must continue to work on logical, short exercises given to them one at a time, in handout format. The inquiry-based approach is intended to increase students' comprehension of what they're doing in the laboratory and why.Wilcox, C. Jayne. J. Chem. Educ.2001, 78, 62.

Comparisons and Demonstrations of Scientific CalculatorsMyung-Hoon Kim, Suw-Young Ly, and Tae-Kee HongScientific calculators are compared in terms of their capacities, featuring many advantages of the graphic calculator over simple nongraphic calculators. Applications in this paper include a simulation of acid-base titration curves, and graphic display of a time course of concentrations of reactants and products for a chemical reaction with first-order kinetics.Kim, Myung-Hoon; Ly, Suw-Young; Hong, Tae-Kee. J. Chem. Educ.2000, 77, 1367.

Acids / Bases |

Kinetics |

Titration / Volumetric Analysis

Pixel Conversion: A Simple Way to Extract Coordinates of Points from a Printed GraphChristian Aymard and Randall B. ShirtsA very simple method is described for extracting the coordinates of points from printed graphs, student reports, or publications. One only needs a flatbed scanner and a desktop computer. This is a convenient and inexpensive alternative to the tedious traditional method using a ruler or to the more costly programs available commercially. A Windows program has been made available to perform the required operations. Aymard, Christian; Shirts, Randall B. J. Chem. Educ.2000, 77, 1230.

Chemometrics

When A + B B + AErling Antony, Lindsay Mitchell, and Lauren NettenstromMany acid-base chemistry demonstrations and laboratory manuals include the "baking soda volcano". Others use the formation of calcium carbonate from calcium hydroxide and carbon dioxide in human breath. This demonstration uses principles from both as well as stoichiometry to answer the question "Does the order of mixing of reagents make a difference?" Antony, Erling; Mitchell, Lindsay; Nettenstrom, Lauren. J. Chem. Educ.2000, 77, 1180.

Acids / Bases |

Stoichiometry |

Reactions

Encouraging Meaningful Quantitative Problem SolvingJeff Cohen, Meghan Kennedy-Justice, Sunny Pai, Carmen Torres, Rick Toomey, Ed DePierro, and Fred GarafaloThis paper describes the efforts of a group of teachers to help college freshman chemistry students and high school science students to improve their problem-solving skills. The presentation includes several sets of questions intended to elucidate ideas and to involve the reader in the process of reflecting upon his or her own problem-solving strategies. Cohen, Jeff; Kennedy-Justice, Meghan; Pai, Sunny; Torres, Carmen; Toomey, Rick; DePierro, Ed; Garafalo, Fred. J. Chem. Educ.2000, 77, 1166.

More Than Meets the Eye: Nonvisual Observations in ChemistryAn adaptation of an acid-base reaction generating carbon dioxide gas that allows blind students to observe the results. This activity is intended to show sighted students that gathering all the information available in the chemistry laboratory will engage all of their senses.J. Chem. Educ.2000, 77, 1104A.

Acids / Bases

Every Year Begins a MillenniumJerry A. BellThis article outlines a series of demonstrations and their contexts, leading to recommendations about what we teach and how we teach.Bell, Jerry A. J. Chem. Educ.2000, 77, 1098.

A Classroom Exercise in Sampling TechniqueMichael R. RossA classroom hands-on demonstration has been developed that looks at the two important sampling considerations, sample size and non-homogeneous sample materials. This classroom activity makes use of readily available M&M candies for the sample size and NERDS for the non-homogeneous sample exercises. Ross, Michael R. J. Chem. Educ.2000, 77, 1015.

Quantitative Analysis |

Chemometrics

Simulating Dynamic Equilibria: A Class ExperimentJohn A. Harrison and Paul D. BuckleyA first-order reversible reaction is simulated on an overhead projector using small coins or discs. Results illustrate how dynamic equilibria are established and allow the introduction of the concept of an equilibrium constant. Le Chtelier's principle is illustrated by further simulations. Harrison, John A.; Buckley, Paul D. J. Chem. Educ.2000, 77, 1013.

Equilibrium |

Rate Law |

Reactions

Two Faces of AlkaloidsJirí DostálThe article discusses and compares the salts and free bases of six well-known alkaloids: nicotine, morphine, cocaine, sanguinarine, allocryptopine, and magnoflorine. Relevance for the biological and medical uses of these compounds is emphasized. Dostál, Jirí. J. Chem. Educ.2000, 77, 993.

Acids / Bases |

Bioorganic Chemistry |

Drugs / Pharmaceuticals |

Natural Products |

Aromatic Compounds |

Medicinal Chemistry

Simulations for Teaching Chemical EquilibriumPenelope A. Huddle, Margaret Dawn White, and Fiona RogersThis paper outlines a systematic approach to teaching chemical equilibrium using simulation experiments that address most known alternate conceptions in the topic. Graphs drawn using the data from the simulations are identical to those obtained using real experimental data for reactions that go to equilibrium. This allows easy mapping of the analogy to the target. Huddle, Penelope Ann; White, Margaret Dawn; Rogers, Fiona. J. Chem. Educ.2000, 77, 920.

Equilibrium |

Learning Theories

Weak vs Strong Acids and Bases: The Football AnalogyTodd P. SilversteinA football analogy for acids and bases in which acids are compared to quarterbacks, whose job is to get rid of the ball (H+). A strong acid, like an excellent quarterback, delivers the ball effectively; a weak acid, like a poor quarterback, is often left holding the ball. Furthermore, bases may be likened to wide receivers, whose job is to catch and hold onto the ball (H+). Silverstein, Todd P. J. Chem. Educ.2000, 77, 849.

Acids / Bases |

Aqueous Solution Chemistry |

Water / Water Chemistry |

Brønsted-Lowry Acids / Bases

A Closer Look at Phase Diagrams for the General Chemistry CourseStephen A. GramschThe information provided by the high-pressure phase diagrams of some simple systems (carbon dioxide, water, hydrogen, and iron) can provide a useful extension to the traditional discussion of phase diagrams in the general chemistry course. At the same time, it can prepare students for a more illuminating presentation of the concept of equilibrium than is possible through the discussion of gas phase, acid-base, and solubility product equilibria alone. Gramsch, Stephen A. J. Chem. Educ.2000, 77, 718.

Modeling Chemical Processes in Seawater Aquaria to Illustrate Concepts in Undergraduate ChemistryGordan GrguricThis paper describes three exercises which can be used in a variety of undergraduate chemistry curricula: (i) determining the salts and their amounts needed to prepare a given volume of artificial seawater, (ii) modeling aqueous carbonate equilibria, to calculate pH and alkalinity shifts through additions of chemicals, and (iii) modeling chemical kinetics involved in aqueous ozone-bromine reactions, to predict the type and extent of disinfection by-products. Grguric, Gordan. J. Chem. Educ.2000, 77, 495.

A Simple Laboratory-Constructed Automatic TitratorKurt L. Headrick, Terry K. Davies, and Aaron N. HaegeleThe construction of a simple automatic titrator is described. The buret is replaced with a metering pump to provide a constant flow of titrant. The output from the pH meter is sent to a recorder via a laboratory- constructed differentiator, allowing the results to be plotted as potential versus time, first or second derivativeHeadrick, Kurt L.; Davies, Terry K.; Haegele, Aaron N. J. Chem. Educ.2000, 77, 389.

Instrumental Methods |

Acids / Bases |

Laboratory Equipment / Apparatus |

Quantitative Analysis |

Titration / Volumetric Analysis

Gas Me Up, or, A Baking Powder DiverHenry R. Derr, Tricia Lewis, and Bretton J. DerrIn this procedure, a pipet that repeatedly submerges and rises to the surface in a tub of water is produced from a beral pipet and baking powder. The procedure works well in outreach activities with children aged 4 to 40 and beyond.Derr, Henry R.; Lewis, Tricia; Derr, Bretton J. J. Chem. Educ.2000, 77, 171.

Acids / Bases |

Gases

SoapmakingThis activity provides a simple experiment that introduces students to an important reaction of organic chemistry. It also helps students connect chemistry to something that they see and use every day and provides an opportunity for cross-curricular work.J. Chem. Educ.1999, 76, 192A.

Acids / Bases |

Industrial Chemistry |

Consumer Chemistry

Environmental Chemistry Using UltrasoundBelinda K. Wilmer, Edward Poziomek, and Grazyna E. OrzechowskaIn this demonstration, we describe a simple method for presenting the usefulness of sonication in environmental chemistry. When an aqueous solution of carbon tetrachloride is sonicated, it degrades to produce HCl and HOCl. These products cause a reduction of pH, which can be observed visually with a pH indicator. Wilmer, Belinda K.; Poziomek, Edward; Orzechowska, Grazyna E. J. Chem. Educ.1999, 76, 1657.

The Softening of Hard Water and Complexometric Titrations: An Undergraduate ExperimentHelena Ceretti, Enrique A. Hughes, and Anita ZaltsAn experiment in which (i) water hardness is explained and demonstrated; (ii) ion-exchange resin properties are visually demonstrated and then used for softening water; (iii) complexometric titrations are used for evaluating water hardness before and after softening; and (iv) acid-base titration can be used to show that the Ca/Mg ions removed by the ion exchanger are replaced by H ions. Ceretti, Helena; Hughes, Enrique A.; Zalts, Anita. J. Chem. Educ.1999, 76, 1420.

Ion Exchange |

Quantitative Analysis |

Titration / Volumetric Analysis |

Water / Water Chemistry |

Acids / Bases

An Acid-Base Chemistry Example: Conversion of NicotineJohn H. SummerfieldThe current government interest in nicotine conversion by cigarette companies provides an example of acid-base chemistry that can be explained to students in the second semester of general chemistry.Summerfield, John H. J. Chem. Educ.1999, 76, 1397.

Acids / Bases |

Drugs / Pharmaceuticals |

Equilibrium

Thermochromism in Commercial ProductsMary Anne White and Monique LeBlancMany commercial products change color with a change of temperature. How do they do it? The processes responsible for the two major categories of commercial thermochromic coloring agents are presented, along with a description of applications of thermochromic materials. White, Mary Anne; LeBlanc, Monique. J. Chem. Educ.1999, 76, 1201.

Acids / Bases |

Consumer Chemistry |

Materials Science |

Applications of Chemistry

Fields of pHPaul Mihas and George PapgeorgiuStudents are taught that the pH of pure water is 7, but the measurement of a sample of distilled water usually gives pH values from 5.5-6.0. In addition, students learn that the ionization of a strong acid determines the pH of an aqueous solution and they cannot distinguish the cases in which ionization of water is significant. Fields of pH was developed to help students overcome such difficulties. Mihas, Paul ; Papgeorgiu, George. J. Chem. Educ.1999, 76, 1032.

Acids / Bases |

Aqueous Solution Chemistry

Predicting Acid-Base Titration Curves without CalculationsDennis W. BarnumIn this paper a qualitative and systematic method for sketching titration curves is presented. Even the more complex cases such as salts or polyprotic acids and bases are treated just as easily as simple monoprotic acids. Having students predict the shape of titration curves from known equilibrium constants helps to focus attention on the general principles without distraction by the mathematics. Barnum, Dennis W. J. Chem. Educ.1999, 76, 938.

Acids / Bases |

Quantitative Analysis |

Water / Water Chemistry |

Equilibrium |

Learning Theories |

Titration / Volumetric Analysis |

Chemometrics

Do pH in Your HeadAddison AultEvery aqueous solution has a pH. Two factors determine this pH: the acidic or basic strength of the solute, and its concentration. When you use pKa values to express acidic and basic strength you can easily estimate the approximate pH of many aqueous solutions of acids, bases, and their salts and their buffers.Ault, Addison. J. Chem. Educ.1999, 76, 936.

The Complexity of Teaching and Learning Chemical EquilibriumLouise Tyson, David F. Treagust, and Robert B. BucatThis paper discusses three key issues relevant to secondary school chemistry teaching. They arise from a study of students' understanding of chemical equilibrium using qualitative and quantitative research methods. Tyson, Louise; Treagust, David F.; Bucat, Robert B. J. Chem. Educ.1999, 76, 554.

Equilibrium |

Learning Theories

Equilibrium Principles: A Game for StudentsLionel J. Edmonson Jr. and Don L. LewisThe laboratory exercise is a game using marked sugar cubes as dice. The game emphasizes the dynamic character of equilibrium. Forward and reverse rate-constant values are used to calculate an equilibrium constant and to predict equilibrium populations. Predicted equilibrium populations are compared with experimental results.Edmonson, Lionel J., Jr.; Lewis, Don L. J. Chem. Educ.1999, 76, 502.

An Easy and Effective Classroom Demonstration of Population DistributionsMarjorie A. JonesUsing a simple experimental design and easily obtained materials, a classroom experiment was conducted to demonstrate normal-distribution behavior for a population. We used popcorn and a hot-air popper. Popped kernels were collected with time and data were plotted as popped kernels per time interval versus time. The data clearly showed a normal (Gaussian) distribution. Jones, Marjorie A. J. Chem. Educ.1999, 76, 384.

The Ammonia Smoke Fountain: An Interesting Thermodynamic AdventureM. Dale AlexanderThe ammonia smoke fountain demonstration utilizes a modification of the apparatus used in the standard ammonia fountain. The modification allows for the introduction of hydrogen chloride gas into a flask of ammonia rather than water. The flow rate of hydrogen chloride gas into the flask in the smoke fountain is not constant, but periodic; that is, the smoke puffs from the end of the tube. This unexpected behavior elicits an interesting thermodynamic explanation.Alexander, M. Dale. J. Chem. Educ.1999, 76, 210.

Acids / Bases |

Gases |

Thermodynamics |

Reactions |

Stoichiometry |

Precipitation / Solubility

Is It Real Gold?Harold H. HarrisThe oxidation-reduction couples involved in the corrosion of gold alloys and the dissolution of "noble" metals are related to an inquiry to the newspaper columnist, Ann Landers. the origin of several contemporary phrases (touch stone, acid test, Hallmark) are found in the chemistry of gold. Harris, Harold H. J. Chem. Educ.1999, 76, 198.

Acids / Bases |

Oxidation / Reduction |

Qualitative Analysis |

Applications of Chemistry

A Unified Titration FormulaP. GlaisterIn a number of standard titrations, a volume of a monoprotic base MOH at a specific concentration is added to a volume of a monoprotic acid HA at a specific concentrations. Four different types of titration are possible, depending on whether the acid and base are strong or weak. A single unifying formula covering all four cases has been determined. Glaister, P. J. Chem. Educ.1999, 76, 132.

Modeling Nuclear Decay: A Point of Integration between Chemistry and MathematicsKent J. Crippen and Robert D. CurtrightA four-part activity utilizing a graphing calculator to investigate nuclear stability is described. Knowledge acquired through the activity provides background for answering the societal question of using nuclear materials for energy production. Crippen, Kent J.; Curtright, Robert D. J. Chem. Educ.1998, 75, 1434.

Nuclear / Radiochemistry |

Atomic Properties / Structure |

Chemometrics

Using Bad Science To Teach Good ChemistryMichael S. EpsteinThis paper presents examples of bad science ranging from "unintentional mistakes" to "fraud" that can be used as part of traditional courses in general and analytical chemistry to encourage scientific reasoning and ethical behavior, and to provide a classroom atmosphere that encourages students to think and learn. Epstein, Michael S. J. Chem. Educ.1998, 75, 1399.

Equilibrium: A Teaching/Learning ActivityAudrey H. WilsonThis article describes hands-on activities for high-school or undergraduate students designed to clarify important concepts involved in early studies of equilibrium. Concepts included are that at equilibrium, rate of forward reaction = rate of backward reaction; concentrations of both reactants and products remain constant; the equilibrium constant is constant at the same temperature but changes as the temperature changes; and equilibrium may be approached from different starting points. Wilson, Audrey H. J. Chem. Educ.1998, 75, 1176.

Equilibrium

"Conceptual Questions" on LeChatelier's PrincipleBenjamin P. HuddleThree "conceptual questions" presented are designed to assess the student's ability to conceptualize chemical equilibrium and to predict the effect of changes made to a system at equilibrium, using LeChatelier's principle, without doing any equilibrium constant calculations.Huddle, Benjamin P. J. Chem. Educ.1998, 75, 1175.

Precision and Accuracy in Measurements: A Tale of Four Graduated CylindersRichard S. TreptowThe concepts of precision and accuracy help students understand that uncertainty accompanies even our best scientific measurements. A model experiment can be used to distinguish the two terms. The experiment uses four graduated cylinders which give measurements of different accuracy and precision. Such terms as mean, range, standard deviation, error, and true value are defined through an illustration.Treptow, Richard S. J. Chem. Educ.1998, 75, 992.

Quantitative Analysis |

Chemometrics

Percent Composition and Empirical Formula - A New ViewGeorge L. GilbertA new method of obtaining the empirical formula for a compound from its percent composition is proposed. The method involves the determination of a minimum molar mass for the compound based on the percentage of each element, obtaining the lowest common molar mass and using this data to calculate the integer values used in writing the empirical formula. Gilbert, George L. J. Chem. Educ.1998, 75, 851.

Atomic Properties / Structure |

Stoichiometry |

Chemometrics

Chemical Domino DemonstrationM. Dale AlexanderThe Chemical Domino Demonstration is both educational and entertaining. It provides an excellent means for a review of chemical concepts at the conclusion of a general chemistry course. This demonstration consists of a number of different chemical reactions occurring in sequence in a Rube Goldberg-type apparatus.M. Dale Alexander. J. Chem. Educ.1998, 75, 490.

Reactions |

Acids / Bases |

Oxidation / Reduction

Mechanism Templates: Lecture Aids for Effective Presentation of Mechanism in Introductory Organic ChemistryBrian J. McNelisTo promote active student learning of mechanism in introductory organic chemistry, hand-outs have been developed with incomplete structures for reaction processes depicted, which are called mechanism templates. The key to these lecture aids is to provide only enough detail in the diagram to facilitate notetaking, ensuring that these templates are dynamic learning tools that must be utilized by an engaged and alert student.Brian J. McNelis. J. Chem. Educ.1998, 75, 479.

Production of Numerical Chemical Problems Using a SpreadsheetPeter G. HallThe use of spreadsheets for "personalized" assignments. These assignments take the form of printed chemical problems such that every student has different numerical data. The problem sets make a challenging student introduction to word processing and spreadsheet use. Hall, Peter G. J. Chem. Educ.1998, 75, 243.

Complexometric Titrations: Competition of Complexing Agents in the Determination of Water Hardness with EDTAM. Cecilia Yappert and Donald B. DuPreThe competition of complexing agents for the same metal ion and the formation of colored metal-ion complexes is demonstrated with the use of an overhead projector. This demonstration can be used to emphasize both the relevance of the relative values of formation constants in the complexation of metal cations and the applicability of complexometric titrations in quantitative chemical analysis. Yappert, M. Cecilia; DuPre, Donald B. J. Chem. Educ.1997, 74, 1422.

Equilibrium |

Coordination Compounds |

Qualitative Analysis |

Quantitative Analysis |

Titration / Volumetric Analysis |

Aqueous Solution Chemistry |

Water / Water Chemistry |

Metals

Formation and Dimerization of NO2 A General Chemistry ExperimentApril D. Hennis, C. Scott Highberger, and Serge Schreiner*A general chemistry experiment which illustrates Gay-Lussac's law of combining volumes. Students are able to determine the partial pressures and equilibrium constant for the formation and dimerization of NO2. The experiment readily provides students with data that can be manipulated with a common spreadsheet. Hennis, April D.; Highberger, C. Scott; Schreiner, Serge. J. Chem. Educ.1997, 74, 1340.

Gases |

Equilibrium |

Quantitative Analysis |

Stoichiometry

A Note on Covariance in Propagation of UncertaintyEdwin F. MeyerIt is pointed out that whenever both the slope and the intercept are used in calculating a physical quantity from a linear regression, propagation of error must include the covariance as well as the variances. The point is illustrated with a calculation of the boiling point of water from the parameters of the lnP vs 1/T fit. If the covariance is omitted from the propagation of error, the estimate of uncertainty is unreasonably large. Meyer, Edwin F. J. Chem. Educ.1997, 74, 1339.

Anthocyanins: A Colorful Class of CompoundsThe red colors of leaves in the fall, and the colors of radish skins, beets, and some cabbages result from pigments known as anthocyanins. This activity makes use of the fact that these substances are also acid-base indicators.J. Chem. Educ.1997, 74, 1176A.

A Study of the pH of Sweat for Horses: A Student-Devised Study by Science and Health Science MajorsJohn Tierney, Lori Peacock, Erica Sorkin, and Susan WareThis article describes the results obtained when the pH for horse sweat was measured. Comparisons with the studies on humans are also noted. The pH of perspiration produced by mares and gelding was measured under controlled conditions and found to be between 6.7 to 10. Tierney, John; Peacock, Lori; Sorkin, Erica; Ware, Susan. J. Chem. Educ.1997, 74, 1135.

Learning Theories |

Acids / Bases |

Drugs / Pharmaceuticals |

Undergraduate Research

Graham's Law and Perpetuation of ErrorStephen J. HawkesGrahams Laws of effusion and diffusion are used in recent articles for traditional experiments to which they do not in fact apply and for which they give the wrong answer.Hawkes, Stephen J. J. Chem. Educ.1997, 74, 1069.

Gases |

Chemometrics |

Transport Properties

The Sodium RainbowMiroslav ProksaA new approach to the reaction of sodium with water to produce a "rainbow" of colors.Proksa, Miroslav. J. Chem. Educ.1997, 74, 942.

Acids / Bases |

Metals |

Oxidation / Reduction

Why and How To Teach Acid-Base Reactions without EquilibriumTerry S. CarltonA stepwise method enables students to predict which acid-base reactions occur when two solutions are mixed. The complexities of equilibrium are avoided by treating reactions as all-or-none and by providing a table of acids in order of strength. Carlton, Terry S. J. Chem. Educ.1997, 74, 939.

Learning Theories |

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Does Copper Metal React with Acetic Acid?Stephen DeMeoStarting with a discrepant event and led through a series of experiments, students of an introductory chemistry course investigate if copper metal reacts with acetic acid. Finding that oxygen from the air plays an important role in the reaction of these substances, students ultimately realize that the conditions under which two reactants interact are important in determining the type of products that are made.DeMeo, Stephen. J. Chem. Educ.1997, 74, 844.

The Chemistry of Paper Preservation: Part 4. Alkaline PaperHenry A. CarterThe use of alkaline paper can minimize the problem of acidity for new papers. This study focuses on the chemistry involved in the sizing of both acid and alkaline papers and the types of fillers used. The advantages and potential problems in alkaline paper making are also discussed. Carter, Henry A. J. Chem. Educ.1997, 74, 508.

Acids / Bases |

Industrial Chemistry |

Applications of Chemistry

Rounding Numbers: Why the "New System" Doesn't WorkW. Robert MiddenThis paper explains a correction to the rounding rule previously published in this Journal. The earlier article reported that the best way to round numbers is to always round up when the first digit dropped is 5. However, this will lead to accumulation of error when errors are averaged.Midden, W. Robert. J. Chem. Educ.1997, 74, 405.

Chemometrics

Sensitivity to Experimental Parameters via SpreadsheetsB. R. SundheimIn spreadsheet computations wherever the functional dependence of calculated results on experimental quantities is obscure, sensitivities may be obtained by testing the effects of variations in relevant inputs. An example is given where Hess' law is explored calorimetrically.Sundhein, B. R. . J. Chem. Educ.1997, 74, 328.

Thermodynamics and SpontaneityRaymond S. OchsDespite the importance of thermodynamics as the foundation of chemistry, most students emerge from introductory courses with only a dim understanding of this subject. Ochs, Raymond S. J. Chem. Educ.1996, 73, 952.

Determination of the Dissociation Constant for Monoprotic Acid by Simple pH MeasurementsR. García-Doménech, J. V. de Julián-Ortiz, G. M. Antón-Fos, and J. Galvez AlvarezThe dissociation constant for a weak monoprotic acid may be calculated in aqueous alkaline solution by straightforward pH measurements, before and after the addition of the acid, and with the advantage of not having to standardize the solutions. García-Doménech, R.; de Julián-Ortiz, J. V.; Antón-Fos, G. M.; Alvarez, J. Galvez. J. Chem. Educ.1996, 73, 792.

SIRS: Simulations and Interactive Resources, IIIMartin, John S.Simulations and Interactive Resources (SIRs) are designed to support interactive lectures in introductory chemistry. This third issue of SIRs includes five new SIRs as well as updated and final versions of all previously published SIRs.Martin, John S. J. Chem. Educ.1996, 73, 722.

Periodicity / Periodic Table |

Equilibrium |

Gases |

Thermodynamics |

Reactions |

Electrochemistry |

Kinetics

Constant-Current Coulometric Titration of Hydrochloric AcidJames Swim, Edward Earps, Laura M. Reed, and David PaulIn this experiment we have combined the titration of a strong acid with a strong base and the electrolysis of water into one complete laboratory experience.James Swim, Edward Earps, Laura M. Reed, and David Paul. J. Chem. Educ.1996, 73, 679.

Titration / Volumetric Analysis |

Acids / Bases |

Water / Water Chemistry |

Electrochemistry |

Oxidation / Reduction

Visible Ion Exchange Demonstration for Large or Small Lecture HallsJerry A. DriscollThis article presents a very simple experiment involving the sense of smell that students can accomplish during lecture. This classroom exercise involves very little preparation time and can be used to illustrate the important concepts of equilibrium along with acid/base properties of various ions.Driscoll, Jerry A. J. Chem. Educ.1996, 73, 639.

Acids / Bases |

Equilibrium

An Approach to Reaction Thermodynamics through Enthalpies, Entropies, and Free Energies of AtomizationJames N. Spencer, Richard S. Moog, and Ronald J. GillespieAn alternative to the conventional method of calculating enthalpies of reaction is presented, using enthalpies of atomization in place of enthalpies of formation. This allows the student to see directly that the reaction enthalpies are determined by the difference in bond strengths in the reactants and products.James N. Spencer, Richard S. Moog, and Ronald J. Gillespie. J. Chem. Educ.1996, 73, 631.

Calorimetry / Thermochemistry |

Thermodynamics |

Equilibrium |

Reactions |

Atomic Properties / Structure |

Stoichiometry

Myths about pH and pH metersSharma, Brahama D.The pH meter does not measure the pH, it measures the E of the cell against a standard.Sharma, Brahama D. J. Chem. Educ.1996, 73, 598.

pH |

Acids / Bases |

Laboratory Equipment / Apparatus

A Simpler Approach to "Apparent" pKa'sKildahl, NicholasAddition to a recent article on pH, indicating an approach which emphasizes the chemistry behind the titration of a weak acid.Kildahl, Nicholas J. Chem. Educ.1996, 73, 598.

pH |

Acids / Bases |

Titration / Volumetric Analysis

All Positive Ions Give Acid Solutions in WaterStephen J. HawkesThe acidity of aqueous solutions of positive ions is never zero although many texts say incorrectly that most metals of Groups I and II and some others are not acidic.Hawkes, Stephen J. J. Chem. Educ.1996, 73, 516.

Acids / Bases |

Metals |

Solutions / Solvents |

pH

Reduction of Viologen Bisphosphonate Dihalide with Aluminum FoilPeter Abeta IyereAn elegant undergraduate experiment similar to the popular "Iodine Clock Reaction" employs the reduction of methyl viologen by hydroxide ion. This demonstration can be used as prelaboratory discussion for an undergraduate kinetic experiment based on the same phenomenon.Iyere, Peter Abeta. J. Chem. Educ.1996, 73, 455.

Kinetics |

Equilibrium

Solubility and Thermodynamics: An Introductory ExperimentRobert G. SilbermanThis article describes a laboratory experiment suitable for high school or freshman chemistry students in which the solubility of potassium nitrate is determined at several different temperatures.Silberman, Robert G. J. Chem. Educ.1996, 73, 426.

Precipitation / Solubility |

Thermodynamics |

Equilibrium

The Teaching of Precipitation Equilibrium: A New ApproachAna M. V. S. V. CavaleiroIn this paper we present a simplified integrated approach to the calculation of the solubility in water of a salt, and the pH of the saturated solution, taking into account the acid-base reactions of the anion. Cavaleiro, Ana M. V. S. V. J. Chem. Educ.1996, 73, 423.

Precipitation / Solubility |

pH |

Solutions / Solvents |

Acids / Bases

Olfactory TitrationJohn T. Wood and Roberta M. EddyThe purpose of this experiment is to use unique acid-base indicator--the odor of raw onion--to indicate the end point of the titration of sodium hydroxide with hydrochloric acid. The use of this novel indicator allows the student to detect the completion of the neutralization reaction by olfaction rather than by sight.Wood, John T.; Eddy, Roberta M. J. Chem. Educ.1996, 73, 257.

Acids / Bases |

Titration / Volumetric Analysis

Curve Fitting: An Alternative Approach to Analyzing Kinetic Data in Introductory ChemistryColeman, William F.183. The availability of high quality software for performing nonlinear curve fitting on microcomputers allows students to take an alternative approach to data analysis, one that concentrates on functional forms that may be more natural than some of the algebraic machinations necessary to render relationships into linear forms. An example of the application of such an approach to the analysis of kinetic data is presented in this paper.Coleman, William F. J. Chem. Educ.1996, 73, 243.

Chemometrics |

Kinetics

Significant Figures in Graph InterpretationDonald M. GrahamA means is derived for calculating the number of significant figures in the slope and intercept of an experimental linear graph. The method is based on the actual scatter in the points rather than on the nominal precision in the original data, and it can be used even by students who are mathematically fairly unsophisticated. Graham, Donald M. J. Chem. Educ.1996, 73, 211.

Chemometrics

Using Quality Circles in General ChemistryKogut, Leonard S.A second semester class in General Chemistry used a student Quality Circle to suggest methods to improve instruction in chemical equilibrium in solution. Kogut, Leonard S. J. Chem. Educ.1996, 73, 146.

The "Magic" FlaskBattino, Rubin; Fortman, John J.Apparatus designed to "magically" dispense liquids of many different colors without refilling.Battino, Rubin; Fortman, John J. J. Chem. Educ.1995, 72, 246.

Not So Late Night Chemistry with USDKoppang, Miles D.; Webb, Karl M.; Srinivasan, Rekha R.Through the program, college students enhance their knowledge and expertise on a chemical topic and gain experience in scientific presentations. They also serve as role models to the high school students who can relate to college students more easily than the chemistry faculty members and their high school students.Koppang, Miles D.; Webb, Karl M.; Srinivasan, Rekha R. J. Chem. Educ.1994, 71, 929.

Forensic Chemistry |

Polymerization |

Electrochemistry |

Isotopes |

Acids / Bases

Chemical Equilibrium in the General Chemistry CourseFainzilberg, Vladimir E.; Karp, StewartThe first chapters on chemical equilibrium in first-year college chemistry texts make an "error" in the solution of certain types of equilibria problems.Fainzilberg, Vladimir E.; Karp, Stewart J. Chem. Educ.1994, 71, 769.

Equilibrium |

Kinetics

Teaching the Truth about pHHawkes, Stephen J.-log[H+] is only an approximation to pH; how to teach pH to avoid misleading students.Hawkes, Stephen J. J. Chem. Educ.1994, 71, 747.

pH |

Acids / Bases |

Aqueous Solution Chemistry |

Equilibrium

Fruit Anthocyanins: Colorful Sensors of Molecular MilieuCurtright, Robert D.; Rynearson, James A .; Markwell, JohnProvides background and references as a starting point for the further exploration of anthocyanins.Curtright, Robert D.; Rynearson, James A .; Markwell, John J. Chem. Educ.1994, 71, 682.

Student's Models of Matter in the Context of Acid-Base ChemistryNakhleh, Mary B.Secondary students' understandings of acids, bases, and pH which emerged in semi-structured interviews conducted as part of a larger study of the effects of three levels of instrumentation on students' understandings of acids, bases, and pH.Nakhleh, Mary B. J. Chem. Educ.1994, 71, 495.

Pictorial Analogies XI: Concentrations and Acidity of SolutionsFortman, John J.Visual analogies of the concentration of a solution, strength of a solution, super saturated solution, conjugate acid-base pairs, and inverse relationship between pH and [H+] and pOH and [OH-].Fortman, John J. J. Chem. Educ.1994, 71, 430.

TITRATE: A Learning Tool for Acid-Base TitrationsRamette, Richard W.Software that calculates and simulates the plot of a titration curve for any base or acid (up to hexaprotic) or any mixture (up to five substances).Ramette, Richard W. J. Chem. Educ.1994, 71, 238.

Acids / Bases |

Titration / Volumetric Analysis |

Aqueous Solution Chemistry

Solving equilibria problems with a graphing calculator: A robust method, free of algebra and calculus Ruch, David K.; Chasteen, T. G.The method of successive approximations is frequently introduced in freshman chemistry as a means for solving equilibrium equations. However, this often requires an understanding of calculus that is problematic for introductory chemistry students. An alternative method to solving such equations is to use graphic calculators to solve problems graphically.Ruch, David K.; Chasteen, T. G. J. Chem. Educ.1993, 70, A184.

How thick/thin is your mirror?McCullough, Thomas; Bell, LisaWhen a student reported that his/her water film was 6 cm thick, these authors felt a review of significant figures and dimensional analysis may be in order.McCullough, Thomas; Bell, Lisa J. Chem. Educ.1993, 70, 851.

Measurement scales: Changing Celsius to Kelvin is not just a unit conversion Nordstrom, Brian H.The key to understanding the difference between Celsius and Kelvin lies in the different types of measurement scales. Students may have an easier time manipulating equations (such as gas laws) if they knew the difference between these scales.Nordstrom, Brian H. J. Chem. Educ.1993, 70, 827.

Chemometrics |

Kinetic-Molecular Theory |

Gases

General treatment of aqueous ionic equilibria using predominance diagramsVale, J.; Fernandez-Pereira, C.; Alcalde, M.This paper illustrates the advantage of a unified instructional treatment based on the similarities o equilibria between acid-base and oxidation-reduction reactions that could be used in a general chemistry course.Vale, J.; Fernandez-Pereira, C.; Alcalde, M. J. Chem. Educ.1993, 70, 790.

Equilibrium calculatorAllendoerfer, RobertA review of a computer program that can calculate equilibrium concentrations of all of the reagents in an arbitrary chemical reaction with as many as five reactants and products.Allendoerfer, Robert J. Chem. Educ.1993, 70, 388.

Equilibrium |

Laboratory Computing / Interfacing

AnswerSheetsCornelius, RichardReview of a spreadsheet-like program that includes modules on significant figures, conversions, stoichiometry, and VSEPR structures.Cornelius, Richard J. Chem. Educ.1993, 70, 387.

VSEPR Theory |

Stoichiometry |

Chemometrics

Chemical checkers on the computerOrlik, Y. G.; Glyakov, P. V.; Varova, R. M.148. Bits and pieces, 49. A program that is enjoyable and useful because it enables students to organize and sum up their knowledge on topics such as chemical properties of metals and properties of acids, bases, and salts.Orlik, Y. G.; Glyakov, P. V.; Varova, R. M. J. Chem. Educ.1993, 70, 297.

Measuring Avogadro's number on the overhead projector Solomon, Sally; Hur, ChinhyuA Petri dish filled with water and stearic acid dissolved in petroleum ether upon an overhead projector can be used to introduce the topic of Avogadro's number.Solomon, Sally; Hur, Chinhyu J. Chem. Educ.1993, 70, 252.

An Investigative Density Experiment Samsa, Richard A.A laboratory exercise about density that is engaging and allows students to use higher-level thinking skills and develop a plan to solve a problem.Samsa, Richard A. J. Chem. Educ.1993, 70, 149.

Laboratory Computing / Interfacing |

Chemometrics |

Physical Properties

More on the Question of Significant FiguresClase, Howard J.Because so many students have a hard time understanding what significant figures are all about, this author developed a method using "?" to substitute for insignificant zeros. This helps many students finally grasp this convention.Clase, Howard J. J. Chem. Educ.1993, 70, 133.

Chemometrics

Equilibrium CalculatorAllendoerfer, RobertThe equilibrium calculator can calculate the equilibrium concentrations of all reagents in an arbitrary chemical reaction with as many as five reactants and products.Allendoerfer, Robert J. Chem. Educ.1993, 70, 126.

Equilibrium |

Chemometrics

The Erosion of Carbonate Stone by Acid Rain: Laboratory and Field InvestigationsBaedecker, Philip A.; Reddy, Michael M.Describes a laboratory experiment on the effects of acidic deposition on carbonate stone erosion. The purpose is to answer questions concerning the effects of hydrogen ion deposition on stone erosion processes that are difficult to resolve in field experiments alone.Baedecker, Philip A.; Reddy, Michael M. J. Chem. Educ.1993, 70, 104.

Is Dimensional Analysis the Best We Have to Offer?Canagaratna, Sebastian G.Dimensional analysis is a unit based approach while the alternative, "method of equations" is a relations-based approach to solving mathematical problems. The author argues that quantitative chemistry involves relationships between quantities and not units, making the later method more pedagogically sound.Canagaratna, Sebastian G. J. Chem. Educ.1993, 70, 40.

On the chemically impossible "other" roots in equilibrium calculations, IILudwig, Oliver G.In a previous paper the author described, using mathematics accessible to students, how an equilibrium calculation leading to a quadratic equation may be shown to have but one "chemical" root. The present work extends this demonstration to some reactions leading to cubic equations.Ludwig, Oliver G. J. Chem. Educ.1992, 69, 884.

The acid equilibrium constant is unity!Baldwin, W. G.; Burchill, C. E.The attempt to assign a non-unity value to this equilibrium constant is a consequence of misunderstanding the way in which the (nearly) constant concentration or activity of the solvent in a dilute solution (or of a pure solid or liquid in a heterogeneous system) is treated when formulating the conventional equilibrium constant expression.Baldwin, W. G.; Burchill, C. E. J. Chem. Educ.1992, 69, 514.

Analogical demonstrations Fortman, John J.By illustrating an analogy with a visual demonstration, a student is aided in both understanding and remembering a lesson.Fortman, John J. J. Chem. Educ.1992, 69, 323.

The use of equilibrium notation in listings of standard potentials.Donkersloot, Maarten C. A.The difficulty in equilibrium notation of standard electrode potentials is due to the convention that half-reactions must be written as reductions if the given potential is to be called a (standard) electrode potential.Donkersloot, Maarten C. A. J. Chem. Educ.1992, 69, 256.

Demonstrations with red cabbage indicator Fortman, John J.; Stubbs, Katherine M.This paper extends the use of the red cabbage extract into demonstrations that illustrate the acidic or basic nature of solutions of gases and gives suggestions for modifications to project the beautiful range of colors and shades for better viewing in large lecture halls.Fortman, John J.; Stubbs, Katherine M. J. Chem. Educ.1992, 69, 66.

Use of liquid oxygen to support combustion Sullivan, Dan M.Production, procedure, and safety of demonstrations involving liquid nitrogen in order to demonstrate: Charles' Law, production and properties of liquid oxygen, effects of concentration on reactions and reaction rates, liquefaction and boiling of oxygen kindling temperature, reactions between substances in two different states of matter, and comparison of partial and complete combustion.Sullivan, Dan M. J. Chem. Educ.1991, 68, 1036.

Physical Properties |

Gases |

Reactions |

Equilibrium

Acid rain investigations Epp, Dianne N.; Curtright, RobertA series of reactions that can be carried out to demonstrate the effects of acid rain.Epp, Dianne N.; Curtright, Robert J. Chem. Educ.1991, 68, 1034.

A procedure for determining formulas for the simple p-block oxoacidsKildahl, Nicholas K.Formulae for p-block oxoacids baffle high school and undergraduate students. This paper presents a procedure for developing these formulas based on the concept of total coordination number of the central atom in the molecule or ion.Kildahl, Nicholas K. J. Chem. Educ.1991, 68, 1001.

Acids / Bases |

Periodicity / Periodic Table

Chemical equations are actually matrix equationsAlberty, Robert A.Chemists tend to think that chemical equations are unique to chemistry and they are not used to thinking of chemical equations as the mathematical equations they in fact are. The objective of this paper is to illustrate the mathematical significance of chemical equations.Alberty, Robert A. J. Chem. Educ.1991, 68, 984.

Demonstration properties of sulfur dioxide Brouwer, H.Demonstrations of properties of sulfur dioxide are timely, given current debates between Canada and the United States regarding acid rain.Brouwer, H. J. Chem. Educ.1991, 68, 417.

Chemical equilibrium: III. A few math tricks Gordus, Adon A.The third article in a series on chemical equilibrium that considers a few math "tricks" useful in equilibrium calculations and approximations.Gordus, Adon A. J. Chem. Educ.1991, 68, 291.

Chemical equilibrium: I. The thermodynamic equilibrium constantGordus, Adon A.This is the first article in a series of eight that investigates the various assumptions that result in the simplified equilibrium equations found in most introductory texts. In this first article, the author considers the general nature of the constant K, Le Chatelier's principle, and the effect of the temperature on K.Gordus, Adon A. J. Chem. Educ.1991, 68, 138.

Thermodynamics |

Equilibrium

Finding largest common factors and simplest integer ratios Macomber, Roger S.General chemistry students can ease some of their math-phobia with an exam question that deals with a familiar topic prior to putting these same mathematical principles into the context of chemistry.Macomber, Roger S. J. Chem. Educ.1991, 68, 42.

Chemometrics

Calculating equilibrium concentrations by the continuation methodCobranchi, Daryl P.; Eyring, Edward M.The use of the continuation method allows the educator to both present more challenging equilibria to the students and to introduce students to another use for a personal computer.Cobranchi, Daryl P.; Eyring, Edward M. J. Chem. Educ.1991, 68, 40.

Accuracy of measurements and the U.S. CensusGorin, GeorgeSome aspects of taking the Census can help students to understand the problem of measurement error and the use of significant figures.Gorin, George J. Chem. Educ.1990, 67, 936.

The pH of any mixture of monoprotic acids and basesHerman, D. P.; Booth, K. K.; Parker, O. J.; Breneman, G. L.115. Bits and pieces, 44. The pH of any mixture of monoprotic weak and strong acids and bases can be calculated. A curve can also be plotted for the titration of the mixture by any monoportic weak or strong acid or base.Herman, D. P.; Booth, K. K.; Parker, O. J.; Breneman, G. L. J. Chem. Educ.1990, 67, 501.

Acids / Bases |

Titration / Volumetric Analysis |

pH

Dynamic data storage in FORTRANChung-Phillips, Alice115. Bits and pieces, 44. The purpose of this article is to promote the use of dynamic storage allocation in FORTRAN to chemistry instructors and students in the present computing environment.Chung-Phillips, Alice J. Chem. Educ.1990, 67, 500.

A small scale equilibrium experiment Flash, PatrickAn alternative method for the experiment in which the equilibrium constant for the iron-thiocyanate complex is determined.Flash, Patrick J. Chem. Educ.1990, 67, 341.

Computer simulation of chemical equilibriumCullen, John F., Jr.108. The "Great Chemical Bead Game" requires no instruments and presents the concepts of equilibrium and kinetics more clearly than an experiment. [October and November Computer Series both inadvertently called number 107. Numbering restored by skipping 109 and calling January 1990 number 110.]Cullen, John F., Jr. J. Chem. Educ.1989, 66, 1023.

Overall chemical equationsGil, Victor M. S.An equation sum can be used safely by itself in stoichiometric and equilibrium calculations only if the intermediates produced in separate reactions are at low steady-state concentrations and if there are no other equilibria involving those species.Gil, Victor M. S. J. Chem. Educ.1989, 66, 324.

Accurate equations of state in computational chemistry projectsAllbee, David; Jones, Edward101. This article presents one method that allows students to become familiar with the use of modern equations of state and also enhances their understanding of how computers can be used in the study and application of chemistry. [Includes "Editor's note: Changes in the computer series", by Lagowski, J. J., p. 226]Allbee, David; Jones, Edward J. Chem. Educ.1989, 66, 226.

Analysis of kinetic data with a spreadsheet programHenderson, JohnAn article about spreadsheet templates that accept concentration versus time data for several runs of an experiment, determination of least-squares lines through data points for each run, and will allow the user to exclude points from the least-squares calculation.Henderson, John J. Chem. Educ.1988, 65, A150.

Chemometrics |

Laboratory Computing / Interfacing |

UV-Vis Spectroscopy |

Rate Law |

Kinetics |

Enzymes

Solution equilibrium problems(Moss, David B.)Cass, Don; Murray, MarileeTwo reviews of a two disk set with a 44-page manual that discusses equilibria in general and specific techniques of solving equilibrium problems.Cass, Don; Murray, Marilee J. Chem. Educ.1988, 65, A114.

Questions from a can of PepsiMitchell, TonyA can of Pepsi can be the starting point of countless chemistry questions that students can relate to. The author encourages other instructors to think about helping students understand chemistry as it relates to contemporary society.Mitchell, Tony J. Chem. Educ.1988, 65, 1070.

Experimental work with tin(II) chloride in a high school Sanchez, Manuela MartinThe author describes a final-project performed by students that integrates concepts of hydrolysis, Le Chatelier's principle, and electrolysis. Students seek answers to questions such as: "What reactions were involved; why is an aqueous solution of SnCl2 acidic; how can elemental tin be recovered from the system?" Sanchez, Manuela Martin J. Chem. Educ.1988, 65, 898.

The perils of carbonic acid and equilibrium constantsJencks, William P.; Altura, Rachel A.It is important to remember that the small amounts of carbon dioxide that are usually present in water can have large effects on acid-base equilibria of dilute solutions and that dilute solutions of most weak acids and bases undergo significant protonation or hydrolysis when they are dissolved in water.Jencks, William P.; Altura, Rachel A. J. Chem. Educ.1988, 65, 770.

Tools of the trade Bruno, Michael J.High school teachers can never have too many visual aids when teaching chemistry. This author shares some demonstrations in equilibrium that often produce "oohs" and "aaaahs" from his students.Bruno, Michael J. J. Chem. Educ.1988, 65, 698.

Equilibrium |

pH

Some analogies for teaching rates/equilibrium Olney, David J.This article presents several analogies for teaching rates and equilibrium developed by the author over his many years in the chemistry classroom that seem to be effective.Olney, David J. J. Chem. Educ.1988, 65, 696.

Let's separate theories from calculations Freilich, Mark B.This author writes in a 'provocative opinion' article challenging the readers to think about heavily emphasizing 'thought problems' in chemistry and allowing students to master those before throwing calculations into the mix.Freilich, Mark B. J. Chem. Educ.1988, 65, 442.

Chemometrics

An alternative to using the PV = nRT equation Desmarais, GeorgeThis author shares his application of the factor-label method to solving gas problems which involves using the ideal gas constant as the starting point in the relationship.Desmarais, George J. Chem. Educ.1988, 65, 392.

Gases |

Stoichiometry |

Chemometrics

A simple, vivid demonstration of selective precipitation Chirpich, Thomas P.A simple, vivid demonstration that is designed to catch the students' attention and illustrate the principles of selective, or fractional, precipitation in action.Chirpich, Thomas P. J. Chem. Educ.1988, 65, 359.

Potentiometric titration of acidic and basic compounds in household cleanersLieu, Van T.; Kalbus, Gene E.The potentiometric titration of commercial household cleaners can be used in student laboratories in freshman, analytical, and physical chemistry courses. It can be used for analysis of household cleaners with either one or two component systems, or it can be used for the determination of the dissociation constant.Lieu, Van T.; Kalbus, Gene E. J. Chem. Educ.1988, 65, 184.

Good numerical technique in chemistry: The quadratic equationThompson, H. BradfordTexts commonly avoid examples with bad round-off problems or handle them by approximation; none of this is necessary, for simple techniques are available to handle quadratic equations easily and precisely.Thompson, H. Bradford J. Chem. Educ.1987, 64, 1009.

Chemometrics

pH measurements on the overhead projectorSolomon, Sally; High, NancyUniversal indicator solution and a corresponding pH indicator chart are used to make pH measurements of an overhead projector where the results are visible to all students in a large lecture hall.Solomon, Sally; High, Nancy J. Chem. Educ.1987, 64, 964.

Mole fraction revisitedMancott, A.This problem requires the use of algebraic reasoning to derive and solve a fraction linear equation based on the concept of moles and conservation of moles.Mancott, A. J. Chem. Educ.1987, 64, 320.

Where did that number come from? DeLorenzo, RonaldWith more careful labeling and handling of numbers, instructors can reduce the confusion students sometimes feel when watching problems being solved by the instructor on the board.DeLorenzo, Ronald J. Chem. Educ.1986, 63, 514.

Chemometrics |

Nomenclature / Units / Symbols

An introductory laboratory exercise for acids and basesMiller, Richard; Silberman, RobertThe authors have used this exercise as an introduction to acid-base chemistry before they do any acid-base titrations in the laboratory.Miller, Richard; Silberman, Robert J. Chem. Educ.1986, 63, 447.

Density gradient columns for chemical displaysGuenther, William B.An important advantage of these demonstrations of complex chemistry is that students can observe them over a period of time as they grasp concepts of solution equilibria.Guenther, William B. J. Chem. Educ.1986, 63, 148.

Mathematics in the chemistry classroom. Part 2. Elementary entities play their partDierks, Werner; Weninger, Johann; Herron, J. DudleyOne of the problems that learners have to overcome when doing stoichiometry calculations is to learn how statements about elementary entities given by formulas and equations are related to statements about portions of substances as measured in the macroscopic world.Dierks, Werner; Weninger, Johann; Herron, J. Dudley J. Chem. Educ.1985, 62, 1021.

Buffer demonstrationOphardt, Charles E.Emphasizes the difference in properties between strong and weak acids and that only a weak acid or base and its salt are a buffer.Ophardt, Charles E. J. Chem. Educ.1985, 62, 608.

An invitation to experiment with an experimentPhanstiel, OttoStudents are asked to develop an experiment in which they isolate an acid / base indicator from a flower and determine the pH at which it changes color.Phanstiel, Otto J. Chem. Educ.1985, 62, 522.

A LAP on moles: Teaching an important conceptIhde, JohnThe objective of the Learning Activity Packet on moles include understanding the basic concept of the mole as a chemical unit, knowing the relationships between the mole and the atomic weights in the periodic table, and being able to solve basic conversion problems involving grams, moles, atoms, and molecules. [Debut]Ihde, John J. Chem. Educ.1985, 62, 58.

Titrator, Review II (Dice, David D.)Drake, Gordon P.Program that allows the user to simulate the titration of either a strong or weak acid with a strong base.Drake, Gordon P. J. Chem. Educ.1984, 61, A273.

Acids / Bases |

Titration / Volumetric Analysis

Titrator, Review I (Dice, David D.)Hill, Sister Mary Mechtilde, RSMProgram that allows the user to simulate the titration of either a strong or weak acid with a strong base.Hill, Sister Mary Mechtilde, RSM J. Chem. Educ.1984, 61, A273.

The factor-label method: Is it all that great?Navidi, Marjorie H.; Baker, A. DavidThe development of reasoning skills in chemistry is better achieved by postponing the introduction of the factor-label method.Navidi, Marjorie H.; Baker, A. David J. Chem. Educ.1984, 61, 522.

Chemometrics

The solubility of NiSO46H2OPacer, Richard A.Approaches the position of equilibrium from both unsaturated and supersaturated solutions.Pacer, Richard A. J. Chem. Educ.1984, 61, 467.

The useless tea kettlePerkins, RobertIf a 2.5 L kettle contains 125 g of calcium carbonate (boiler scale), how many times would the kettle have to be filled with distilled water to remove all of the deposits given the Ksp of calcium carbonate?Perkins, Robert J. Chem. Educ.1984, 61, 383.

Precipitation / Solubility |

Acids / Bases |

Aqueous Solution Chemistry |

Solutions / Solvents

Cooking with chemistryGrosser, Arthur E.Two demonstrations involving cooking eggs and suggestions for many more examples of cooking that illustrate important principles of chemistry. From the "State-of-the-Art Symposium for Chemical Educators: Chemistry of the Food Cycle".Grosser, Arthur E. J. Chem. Educ.1984, 61, 362.

Metal-ligand complexes-a calculation challengeRamette, R. W.The purpose of this paper is to illustrate one of the most important experimental methods for studying complex equilibria and to present synthetic data as a challenge to the many sophisticated calculation procedure that enjoy various degrees of loyalty around the world.Ramette, R. W. J. Chem. Educ.1983, 60, 946.

Reflections upon mathematics in the introductory chemistry courseGoodstein, Madeline P.It is the purpose of this paper to call attention to the lack of mathematical competence by chemistry students and to invite consideration of one conceptual scheme which may be used to unify the mathematical approach.Goodstein, Madeline P. J. Chem. Educ.1983, 60, 665.

Chemometrics |

Gases

NH4HC03: a stimulant for learningRichards, R. RonaldStudents, professors, and the literature have all been confused by the unusual dissociation equilibrium of NH4HCO3.Richards, R. Ronald J. Chem. Educ.1983, 60, 555.

Equilibrium |

Amines / Ammonium Compounds |

Gases

On the chemically impossible "other" roots in equilibrium problemsLudwig, Oliver G.Students often have a hard time knowing when to disregard equilibrium roots that are too large or are negative. The author suggests a convincing proof that helps students understand how the relationship between the conceptual and mathematical.Ludwig, Oliver G. J. Chem. Educ.1983, 60, 547.

Equilibrium |

Chemometrics

Empirical pKb and pKa for nonmetal hydrides from periodic table positionBayless, Philip L.The equation in this article was developed by the author. It estimates the aqueous pKa for certain acids to an average deviation of 0.1pK unit for those with experimentally determined values and agrees with experimentally determined values, and as well as with estimates for those too weak or too strong to be measured.Bayless, Philip L. J. Chem. Educ.1983, 60, 546.

Le Châtelier's principle: the effect of temperature on the solubility of solids in liquidsBrice, L. K.The purpose of this article is to provide a rigorous but straightforward thermodynamic treatment of the temperature dependence of solubility of solids in liquids that is suitable for presentation at the undergraduate level. The present discussion may suggest how to approach the qualitative aspects of the subject for freshman.Brice, L. K. J. Chem. Educ.1983, 60, 387.

Mass spectral analysis of halogen compounds Holdsworth, David K.37. Bits and pieces, 14. A pocket calculator can be programmed to decide and display the halogen combination in a molecular-ion cluster by examination of the (M+2)/M or (X+2)/X percentage values.Holdsworth, David K. J. Chem. Educ.1983, 60, 103.

Mathematics in data analysis: An introductionWang, TaitzerThe meaning of simple mathematical equations are described in a perspective that, for some reasons, many beginning students do not seem to be able to obtain from reading textbooks on the subject.Wang, Taitzer J. Chem. Educ.1982, 59, 592.

A physical model to demonstrate acid-base conjugate pairsNaylor, Robert W.There seems to be a great deal of confusion among students over the relationship of the strength of a conjugate acid or base to its respective precursor. Using magnets, an extremely simple method of demonstrating that weak acids give strong bases and vice versa can be easily performed.Naylor, Robert W. J. Chem. Educ.1981, 58, 1017.

Acids / Bases

Red cabbage and the electrolysis of waterSkinner, James F.The demonstration profiled here has proven effective in bringing together concepts from acid-base chemistry and electrochemistry.Skinner, James F. J. Chem. Educ.1981, 58, 1017.

Electrochemistry |

Water / Water Chemistry |

Acids / Bases

Red cabbage and the electrolysis of waterSkinner, James F.The demonstration profiled here has proven effective in bringing together concepts from acid-base chemistry and electrochemistry.Skinner, James F. J. Chem. Educ.1981, 58, 1017.

Electrochemistry |

Water / Water Chemistry |

Acids / Bases

Think Wheeler, S. J., James D.Students have an easy enough time crunching numbers, but it is alarming how little they understand the concepts behind the numbers. Students should not be making remarks such as, "If they keep changing how they write the problems, how am I supposed to know how to solve them?"Wheeler, S. J., James D. J. Chem. Educ.1981, 58, 1004.

Learning Theories |

Chemometrics

Small things and large numbers Rosenberg, Milton H.Some challenging solubility problems are featured in this note.Rosenberg, Milton H. J. Chem. Educ.1981, 58, 962.

Pressure and the exploding beverage container Perkins, Robert R.The question in this article is an extension of exploding pop bottles to illustrate the balancing of a chemical equation, enthalpy, stoichiometry, and vapor pressure calculations, and the use of the Ideal Gas Equation. The question is aimed at the first-year level student.Perkins, Robert R. J. Chem. Educ.1981, 58, 363.

Stoichiometry |

Gases |

Thermodynamics |

Chemometrics

The "chemical fountain": An old experiment in a new settingBen-Zvi, Ruth; Silberstein, JudithA new teaching sequence was developed for an introductory high school chemistry course. In this teaching sequence experiments are designed so as to capture student interest, enhance their motivation, and get them involved in the learning process.Ben-Zvi, Ruth; Silberstein, Judith J. Chem. Educ.1981, 58, 68.

Amines / Ammonium Compounds |

Acids / Bases

Soil analysis for high school chemistry studentsEisenmann, Mary A.Students examine the solubility of nitrate ions, the insolubility of iron hydroxide and iron carbonate, and the reaction between acid and carbonates.Eisenmann, Mary A. J. Chem. Educ.1980, 57, 897.

Empirical formulas - A ratio problemKnox, KerroA problem involving an analogy between ratios of boys to girls given their average weights and percentage composition of the class by weight.Knox, Kerro J. Chem. Educ.1980, 57, 879.

A chemistry lesson at Three Mile IslandMammano, Nicholas J.Teaching principles of general chemistry through references made to the nuclear incident at Three Mile Island.Mammano, Nicholas J. J. Chem. Educ.1980, 57, 286.

Equilibrium |

Gases |

Stoichiometry |

Nonmajor Courses |

Nuclear / Radiochemistry |

Applications of Chemistry

"To sink or swim"O'Connor, RodA problem regarding the maximum water hardness that can be permitted in a swimming pool if it is desired to avoid calcite formation given the carbonate ion concentration. [Debut]O'Connor, Rod J. Chem. Educ.1980, 57, 151.

Strong and weak acids and basesDeck, Joseph C.The designations "strong" and "weak" are used in various ways, and often with respect to the same compound in different situations.Deck, Joseph C. J. Chem. Educ.1979, 56, 814.

Pepsin and antacid therapy: A dilemmaLaswick, Patty H.; Batson, W. BraytonIllustrates some areas of uncertainty in the current literature regarding the mechanism of digestion and presents an experiment that is more consistent with current biochemical research.Laswick, Patty H.; Batson, W. Brayton J. Chem. Educ.1979, 56, 484.

The temperature dependence of the equilibrium constantBurness, James H.This exam question tests a student's ability to derive the temperature dependence of an equilibrium constant not by qualitatively applying Le Chatelier's principle, but by understanding the relationship between the kinetics of the equation and the value of Keq.Burness, James H. J. Chem. Educ.1979, 56, 395.

Antacids as an extension to neutralizationSmith, Douglas D.Examines a number of antacids for their suitability for use in studying acid-base behavior in the laboratory.Smith, Douglas D. J. Chem. Educ.1979, 56, 338.

Acids / Bases |

Consumer Chemistry

Antacids as an extension to neutralizationSmith, Douglas D.Examines a number of antacids for their suitability for use in studying acid-base behavior in the laboratory.Smith, Douglas D. J. Chem. Educ.1979, 56, 338.

Buffer effect demonstration on the overhead projectorHobe, Paul G., Jr.Illustrates that one drop of dilute acid or base will change the pH of water by a large amount while larger amounts can be added to a buffer solution before any change is noted.Hobe, Paul G., Jr. J. Chem. Educ.1979, 56, 47.

Intuitive and general approach to acid-base equilibrium calculationsFelty, Wayne L.The purpose of this paper is to show that the usual intuitive approach used in general chemistry can be readily extended without introduction of additional, sophisticated concepts to give the general, exact expression and to point out the pedagogical advantage of its use.Felty, Wayne L. J. Chem. Educ.1978, 55, 576.

Acids / Bases |

Equilibrium |

Chemometrics

Pressure calculations Schultz, Charles W.This question requires students to be able to distinguish two kinds of pressure: Boyles law pressure of gas (that depends on volume) from the equilibrium vapor pressure above a liquid (that does not).Schultz, Charles W. J. Chem. Educ.1978, 55, 515.

Gases |

Chemometrics

Development of intellectual skills in the laboratoryOphardt, Charles E.This first semester laboratory was designed to give instruction and practice in the intellectual skills of application, analysis, synthesis, and in Piaget's formal operations.Ophardt, Charles E. J. Chem. Educ.1978, 55, 485.

Teaching the method of successive approximationsNassiff, Peter J.; Boyko, E. R.The purpose of this papers is to help the teacher show the student why basic methods of successive approximations work, how they may be applied, and under what conditions it will be successful.Nassiff, Peter J.; Boyko, E. R. J. Chem. Educ.1978, 55, 376.

Temperature dependence of Kw Steffel, M. J.The question presented in this note requires the resolution of a conflict between a common sense notion and an isolated fact.Steffel, M. J. J. Chem. Educ.1978, 55, 243.

The chemical equation. Part I: Simple reactionsKolb, DorisA chemical equation is often misunderstood by students as an "equation" that is used in chemistry. However, a more accurate description is that it is a concise statement describing a chemical reaction expressed in chemical symbolism.Kolb, Doris J. Chem. Educ.1978, 55, 184.

Water dipping kinetics. A physical analog for chemical kineticsBirk, James P.; Gunter, S. KayPhysical analogs of zero-, first, and second-order kinetics using the volume of water transferred by a dipper oriented in different directions with respect to a basin of water.Birk, James P.; Gunter, S. Kay J. Chem. Educ.1977, 54, 557.

Quality levels and the Brønsted theoryBank, EvelynMaintaining standards for a diversity of students and teaching hydrolysis with the Bronsted-Lowry theory. [Debut]Bank, Evelyn J. Chem. Educ.1977, 54, 548.

Le Chtelier's principle: A laboratory exerciseFriedman, FredericaLe Chtelier's principle can be demonstrated by showing that water can boil at temperatures below 100C due to reduced vapor pressure.Friedman, Frederica J. Chem. Educ.1977, 54, 236.

Equilibrium |

Phases / Phase Transitions / Diagrams |

Gases |

Water / Water Chemistry

Effect of Ionic Strength on Equilibrium ConstantsSeymour, M. D.; Fernando, QuintusInvolves the determination of the acid dissociation constant of bromcresol green by a spectrophotometric method; using a graphing calculator, each student can perform the laboratory work and obtain his own data set.Seymour, M. D.; Fernando, Quintus J. Chem. Educ.1977, 54, 225.

Separation of an APC mixture. A quantitative analysis experimentHaddad, Paul; Rasmussen, MalcolmIn this paper the well known technique of pH, controlled extractive separation of a mixture of an acidic, basic, and neutral organic substance has been applied to separation and analysis of a mixture of the drugs aspirin, caffeine, and phenacetin.Haddad, Paul; Rasmussen, Malcolm J. Chem. Educ.1976, 53, 731.

Cookbook dimensional analysisDeLorenzo, RonaldFrequently, teachers will hear, "...it looks easy when you do it..." when teaching dimensional analysis. This teacher advises others on a way to help students gain self-efficacy with this problem solving-strategy.DeLorenzo, Ronald J. Chem. Educ.1976, 53, 633.

A new buffer demonstrationFriedman, NormanAn Alka-Seltzer tablet in water is used as a buffer system and its resistance to changes in pH are compared to solutions of buffered aspirin and aspirin.Friedman, Norman J. Chem. Educ.1975, 52, 605.

Maximizing profits in equilibrium processesRish, Ronald J.Provides the student with an example in which both chemical principles and calculus are applied to a realistic industrial situation where profits are a must.Rish, Ronald J. J. Chem. Educ.1975, 52, 441.

Equilibrium |

Industrial Chemistry |

Chemometrics

Demonstrations for high school chemistryCastka, Joseph F.A sequence of demonstrations that may serve to initiate and maintain student interest in the development of acid-base theories and bond strength.Castka, Joseph F. J. Chem. Educ.1975, 52, 394.

Molar solubility calculations and the control equilibriumChaston, S. H. H.The Control-Equilibrium method uses as its starting point a precise procedure for obtaining the equilibrium that accounts for the bulk of the decomposition of starting materials.Chaston, S. H. H. J. Chem. Educ.1975, 52, 206.

The aspirin project. Laboratory experiments for introductory chemistryBrown, David B.; Friedman, Lawrence B.This laboratory project involves the synthesis, characterization, and study of some reactions of acetylsalicylic acid, and the comparison of acetylsalicylic acid with the major components of various commercial brands of aspirin tablets.Brown, David B.; Friedman, Lawrence B. J. Chem. Educ.1973, 50, 214.

Conjugate acid-base and redox theoryPacer, Richard A.Consideration of relative oxidizing / reducing strength would be greatly facilitated if this topic were presented in terms of transfer of one or more electrons between members of a conjugate redox pair.Pacer, Richard A. J. Chem. Educ.1973, 50, 178.

Extraction of acid with aqueous baseSilversmith, Ernest F.This is a visual demonstration of the principle that acidic organic substances can be extracted from an organic solvent via conversion to a salt, and the latter extracted from the aqueous solution via reconversion to the acid form.Silversmith, Ernest F. J. Chem. Educ.1972, 49, A694.

Safe handling of the perchloric acid in the laboratoryMuse, Lowell A.Following a perchloric acid explosion at the University of Georgia, a practical set of recommendations for the safe handling and storage of perchloric acid was developed.Muse, Lowell A. J. Chem. Educ.1972, 49, A463.

The design and use of an equilibrium machineAlden, Robert T.; Schmuckler, Joseph S.An operating model that can be used to determine quantitatively equilibrium shifts when demonstrating Le Chatelier's Principle and relates to molecular level considerations and the probabilistic nature of equilibrium.Alden, Robert T.; Schmuckler, Joseph S. J. Chem. Educ.1972, 49, 509.

Using alligation alternate to solve composition problemsMancott, AnatolProblems involving the composition of mixtures may be solved by using the relatively obscure method of "alligation alternate" in lieu of the standard algebraic procedure with no loss in accuracy; includes five examples.Mancott, Anatol J. Chem. Educ.1972, 49, 57.

SI units in physico-chemical calculationsNorris, A. C.This article demonstrates how the adoption of SI units affects some of the more important physico-chemical calculations found at the undergraduate level.Norris, A. C. J. Chem. Educ.1971, 48, 797.

Nomenclature / Units / Symbols |

Chemometrics

Beginning chemistry can be relevantCorwin, James F.The continuing criticism offered by students of the science that the present day courses are not relevant to contemporary problems. This can be answered in part by a laboratory program based on environmental problems.Corwin, James F. J. Chem. Educ.1971, 48, 522.

MiscellaneousAlyea, Hubert N.These twelve overhead projection demonstrations include rates of reactions, clock reactions, the effect of temperature and the presence of a catalyst on the decomposition of hydrogen peroxide, the relationship between viscosity and temperature, equilibria, solubility product, and the common ion effect.Alyea, Hubert N. J. Chem. Educ.1970, 47, A437.

Prolonging death (in apples)Plumb, Robert C.Using controlled atmosphere storage to prolong the freshness of vegetables and fruits after they have been harvested.Plumb, Robert C. J. Chem. Educ.1970, 47, 518.

Equilibrium |

Kinetics |

Agricultural Chemistry |

Applications of Chemistry |

Gases

The use of specific ion electrodes for equilibrium measurementsWilliams, T. R.; Boettner, Wayne; Wakeham, StuartThe purpose of this investigation is to suggest the variety of information that can be obtained using specific ion electrodes.Williams, T. R.; Boettner, Wayne; Wakeham, Stuart J. Chem. Educ.1970, 47, 464.

Sealed tube experimentsCampbell, J. A.Lists and briefly describes a large set of "sealed tube experiments," each of which requires less than five minutes to set-up and clean-up, requires less than five minutes to run, provides dramatic results observable by a large class, and illustrates important chemical concepts.Campbell, J. A. J. Chem. Educ.1970, 47, 273.

Hydrolysis of sodium carbonateNakayama, F. S.Presents a procedure for obtaining the ion concentrations of the various component species produced by the hydrolysis of sodium carbonate.Nakayama, F. S. J. Chem. Educ.1970, 47, 67.

Computer programs for calculating pHSchlessinger, Gert G.A brief note on the availability of a Fortran II program for calculating the pH of weak acids and bases and salts of these species in aqueous solution.Schlessinger, Gert G. J. Chem. Educ.1969, 46, 680.

The law of mass actionBerline, Steven; Bricker, ClarkIt is the purpose of this paper to present a derivation of the Law of Mass Action that should have meaning and could be used at an elementary level.Berline, Steven; Bricker, Clark J. Chem. Educ.1969, 46, 499.

Monoprotic or diprotic?Goldman, James A.The author demonstrates that the results of an earlier article are not altogether unexpected.Goldman, James A. J. Chem. Educ.1969, 46, 123.

Acids / Bases |

Aqueous Solution Chemistry |

pH

Chemical queries. Especially for introductory chemistry teachersYoung, J. A.; Malik, J. G.(1) Is there such a thing as a negative pH value? Or one above 14? (2) What is entropy, in terms a beginner may understand? (3) On calculating the molecular weight of a solute from concentration and freezing point depression.Young, J. A.; Malik, J. G. J. Chem. Educ.1969, 46, 36.

From stoichiometry and rate law to mechanismEdwards, John O.; Greene, Edward F.; Ross, JohnExamines the rules used by chemists as guidelines in developing mechanisms from stoichiometric and rate law observations. Edwards, John O.; Greene, Edward F.; Ross, John J. Chem. Educ.1968, 45, 381.

Dissociation of weak acids and bases at infinite dilutionStock, D. IrwinIt is all too easy to forget that in a solution of infinite dilution the solvent itself is ionized to an extent governed by its ionization constant, and that the concentration of its ions will appear in the expression for the dissociation constant of the solute.Stock, D. Irwin J. Chem. Educ.1967, 44, 764.

A new twist to Ksp evaluationHazel, J. FredEvaluating the concentration of slightly soluble slats by passing the saturated solution through a cation resin and titrating the resulting acid in the eluate.Hazel, J. Fred J. Chem. Educ.1966, 43, 636.

Theoretical error in acid-base titrationsButcher, John; Quintus, FernanadoThe purpose of this report is to describe simple derivations of equations for titration error calculations for a number of acid-base titrations, and to show error curves for some typical cases.Butcher, John; Quintus, Fernanado J. Chem. Educ.1966, 43, 546.

Teaching ionic equilibrium: Use of log chart transparenciesFreiser, Henry; Fernando, QuintusThe use of graphical methods brings the problem of significance of various terms in complicated expressions into proper focus. Furthermore, a pictorial representation permits the student to see at a glance how the concentrations of various species in a system at equilibrium change with conditions.Freiser, Henry; Fernando, Quintus J. Chem. Educ.1965, 42, 35.

Sulfuric acid and the hydrated hydronium ionJurale, BernardDescribes how the sulfuric acid-water system can be used to establish the identity of the hydronium and hydrated hydronium ions.Jurale, Bernard J. Chem. Educ.1964, 41, 573.

The Carnot cycle and Maxwell's relationsNash, Leonard K.Maxwells equations can be derived from nothing more than the Carnot cycle and the deployment of the simplest plane geometry.Nash, Leonard K. J. Chem. Educ.1964, 41, 368.

Thermodynamics |

Chemometrics

Beer's law without calculusPinkerton, Richard C.There is no good reason for using calculus in the presentation of Beer's law.Pinkerton, Richard C. J. Chem. Educ.1964, 41, 366.

Development of the pH concept: A historical surveySzabadvary, Ferenc; Oesper, Ralph E., trans.Traces the historical development of the following: a recognition of the importance of hydrogen ion concentration; an understanding of buffer solutions; and the concept and measurement of pH.Szabadvary, Ferenc; Oesper, Ralph E., trans. J. Chem. Educ.1964, 41, 105.

The hydrated hydronium ionClever, H. LawrenceIt is the purpose of this brief review to cite and discuss some of the evidence for the existence of the trihydrated hydronium ion.Clever, H. Lawrence J. Chem. Educ.1963, 40, 637.

Equilibria in ionic solutionsKokes, R. J.; Dorfman, M. K.; Mathia, T.In conjunction with lectures on equilibria in electrolytic solutions, students perform a set of laboratory experiments in which they determine both the ionization constant of chloroacetic acid and the solubility of its silver salt.Kokes, R. J.; Dorfman, M. K.; Mathia, T. J. Chem. Educ.1962, 39, 93.

A simple method for finding slopesHoare, James P.Describes a simple method for determining the tangent at any point on a given curve using a solid glass rod.Hoare, James P. J. Chem. Educ.1961, 38, 570.

Chemometrics

Easily prepared wide range buffer seriesCarmody, Walter R.A series of buffers with pH values ranging from 2.0 to 12.0 that requires the preparation of only two stock solutions and requires only three common chemicals.Carmody, Walter R. J. Chem. Educ.1961, 38, 559.

Aqueous Solution Chemistry |

Acids / Bases |

pH |

Laboratory Management

Heat of reaction and H2SO4 concentration: A general chemistry experimentWolthuis, Enno; Leegwater, Arie; Ploeg, John VanderThis procedure measures the heat of reaction between water and sulfuric acid of various concentrations; this information is used to determine the concentration of an unknown acid sample.Wolthuis, Enno; Leegwater, Arie; Ploeg, John Vander J. Chem. Educ.1961, 38, 472.

The equilibria of complex formationBanks, James E.Despite the present recognition of the stepwise formation of complexes in solution, many textbooks continue to treat it as a one-step process, presumably to preserve a reasonable simplicity in the mathematical computation of concentrations.Banks, James E. J. Chem. Educ.1961, 38, 391.

Equilibrium |

Coordination Compounds |

Aqueous Solution Chemistry

Is there an alternative to pH?Crane, Francis E., Jr.Provides some alternatives to the traditional definition of pH that introductory students may find more intuitive and less confusing.Crane, Francis E., Jr. J. Chem. Educ.1961, 38, 365.

pH |

Acids / Bases |

Nomenclature / Units / Symbols

An approach to complex equilibrium problemsButler, James N.Presents an approach to equilibrium problems that sets up enough equations relating the various concentrations present to define the system completely and then makes approximations that simplify the equations.Butler, James N. J. Chem. Educ.1961, 38, 141.

Potentiometric measurements of equilibria: In general chemistry laboratoryChesick, J. P.; Patterson, Andrew, Jr.The authors describe an experiment in which the solubility product of silver chloride, the ionization constant of the silver-ammonia complex, and the ionization constant of acetic acid can be determined with one afternoon of work.Chesick, J. P.; Patterson, Andrew, Jr. J. Chem. Educ.1959, 36, 496.

Electrochemistry |

Equilibrium |

Precipitation / Solubility |

Aqueous Solution Chemistry |

Acids / Bases

Titration without buretsGaddis, Shirley W.Describes the use of small polyethylene bottles to measure the acid strength of vinegar.Gaddis, Shirley W. J. Chem. Educ.1959, 36, 290.

Acids / Bases |

Aqueous Solution Chemistry |

Titration / Volumetric Analysis |

Qualitative Analysis |

Laboratory Equipment / Apparatus

The chemistry of silicic acidGreenberg, S. A.This article attempts to address the many incorrect concepts regarding silicic acid that still appear in textbooks and the literature.Greenberg, S. A. J. Chem. Educ.1959, 36, 218.

Acids / Bases

Dynamic equilibrium: A student demonstrationKauffman, George B.Dynamic equilibrium is demonstrated by students pouring water back and forth between containers using different sized beakers. Kauffman, George B. J. Chem. Educ.1959, 36, 150.

An exact titration equationBolie, Victor W.The purpose of this paper is to show the development of a titration equation for a precipitation reaction which is exact in the mathematical sense.Bolie, Victor W. J. Chem. Educ.1958, 35, 449.

Titration / Volumetric Analysis |

Chemometrics |

Undergraduate Research

Research project for general chemistry laboratorySchwolow, JeanIn order to modify the routine experiment in which students know the answers before ever entering the laboratory, freshmen were presented with a simulated research project connected with acids, bases, and pH measurements.Schwolow, Jean J. Chem. Educ.1958, 35, 416.

The analyst and the inconstant constantsRingbom, AndersSimple theories taught to freshmen often do not agree well with experimental data; the author examines the case of equilibrium constants and elaborates on a method of dealing with this problem.Ringbom, Anders J. Chem. Educ.1958, 35, 282.

Amphoteric molecules, ions and saltsDavidson, DavidIt is the aim of this paper to call attention to the splendid opportunity amphoteric substances afford for the teaching of acid-base principles.Davidson, David J. Chem. Educ.1955, 32, 550.

Le Châtelier's principle and the equilibrium constantMiller, Arild J.Many students of chemistry have difficulty in understanding how the position of equilibrium in a gaseous reaction can change when the pressure is altered, in accordance with Le Châtelier's principle, without causing a corresponding variation in the equilibrium constant.Miller, Arild J. J. Chem. Educ.1954, 31, 455.

Equilibrium |

Reactions |

Gases

Proper place problemsMacKenzie, ScottA mathematical analysis of evaluating problems in which students are asked to place items in the correct order.MacKenzie, Scott J. Chem. Educ.1954, 31, 428.

Solubility of silver salts in aqua ammoniaJohnson, Clyde R.Examines two problems regarding the calculation of the solubility of a silver salt in aqua ammonia of a given concentration.Johnson, Clyde R. J. Chem. Educ.1954, 31, 205.

Praseodymium tetrafluoridePerros, Theodore P.; Munson, Thomas R.; Naeser, Charles R.In spite of the experimental failures to prepare praseodymium tetrafluoride, there is strong evidence for its possible formation to be found by calculating the equilibrium constants for some of the reactions by which this compound might be prepared.Perros, Theodore P.; Munson, Thomas R.; Naeser, Charles R. J. Chem. Educ.1953, 30, 402.

A common misunderstanding of Hess' lawDavis, Thomas. W.The statement, sometimes attributed to Hess, that "In any series of chemical or physical changes the total heat effect is independent of the path by which the system goes from its initial to its final state" is incorrect.Davis, Thomas. W. J. Chem. Educ.1951, 28, 584.

Stoichiometry |

Acids / Bases |

Aqueous Solution Chemistry |

Calorimetry / Thermochemistry

The overhead projector and chemical demonstrationsSlabaugh, W. H.Chemical demonstrations described for use with an overhead projector include the relative activity of metals, the electrolysis of water, the random motion of gas molecules, the action of metal couples, the relative strength of acids, the qualitative aspects of optical activity, and electrochemistry.Slabaugh, W. H. J. Chem. Educ.1951, 28, 579.